Columbia  (Bnitiers^itp 
mtlieCftpotlmigork  c»j^.  »L 

College  of  ^fjpsiitiang  anb  burgeons; 


NOTHING  is  more  worthless  than 
an  incorrect  diagnosis,  and  no 
matter  how  well  the  wrong  treat- 
ment is  applied,  it  remains  the  wrong 
treatment.  First  of  all,  then,  make 
a  correct  diagnosis. 

H.  R.  R. 


ELECTRO-RADIOGRAPHIC  DIAGNOSIS 


Digitized  by  the  Internet  Archive 

in  2010  with  funding  from 

Open  Knowledge  Commons 


http://www.archive.org/details/electroradiograpOOrape 


ELECTRO-RADIOGRAPHIC 
DIAGNOSIS 


A  Book  on  the  Electric  Test  for  Pulp  Vitality,  Giving  the  Technic 

OF  Its  Use  in  Detail  and  Submitting  Clinical  Evidence  of 

Its  Absolute  Necessity  to  Dental  Diagnosis 


BY 
HOWARD  RILEY  RAPER,  D.D.S. 

Formerly  Professor  of  Radiodontia,  Materia  Medica  and  Operative  Technic, 

and  Junior  Dean,  Indiana  Dental  College;  Author  of 

"Elementary  and  Dental  Eadiography. " 


WITH  135  ILLUSTRATIONS 


ST.  LOUIS 

C.  V.  MOSBY  COMPANY 

1921 


1^     ^ 


Copyright,  1921,  by  C.  V.  Mosby  Company 


(Printed  in  U.  S.  A.) 


Press  of 

C.  V.  Mosby  Compa/iy 

St.    Louis 


TO 

MY  IDEA^ 

OF  A  MOTHEE 

THAT  IS^ 

TO 

MY  MOTHER 


PREFACE 


The  object  of  this  little  book  is  to  help  bring  the  electric 
test  for  pulp  vitality  into  its  deserved  popularity  and  the 
writer  hopes  to  accomplish  this  by  doing  two  things :  (1) 
By  showing  how  frequently  the  test  is  necessary  to  cor- 
rect dental  diagnosis  and  (2)  by  teaching  in  detail  the 
technic  of  its  application. 

Every  dentist  who  has  an  x-ray  machine,  and  every 
dentist  who  does  not  have  an  x-ray  machine,  should  use 
the  electric  test  for  pulp  vitality.  In  short  the  electric 
test  is  of  the  utmost  value  to  any  one  who  attempts  dental 
diagnosis.  It  is  often  absolutely  indispensable  to  correct 
diagnosis,  of  which  fact  the  reader  will  be  convinced,  I 
believe,  by  reading  Chapters  X  and  XI. 

The  writer  has  had  most  of  the  notes  used  in  the  writ- 
ing of  this  little  book  in  his  possession  since  1916,  at  that 
time,  I  dare  say,  there  were  not  fifty  dentists  in  the 
United  States  using  the  test.  In  the  past  four  years  the 
test  has  commenced  to  receive  a  wider  recognition.  But 
even  yet  only  a  comparatively  few  dentists  use  it.  The 
reasons  for  this,  it  seems  to  me  are:  First,  the  value  and 
importance  of  the  test  are  not  fully  appreciated.  Second, 
the  necessity  of  acquiring  knowledge  of  correct  technic  is 
not  appreciated.  Third,  the  dental  electrodes  in  use  are 
inadequate.    Let  us  consider  each  of  the  foregoing. 

First,  the  value  and  importance  of  the  test :  I  believe  I 
am  right  in  saying  that,  with  a  few  exceptions,  the  only 
men  to  have  a  really  comprehensive  idea  of  the  impor- 
tance of  the  electric  test  as  a  diagnostic  measure  are  a 
few  radiodontists.  The  electric  test  for  pulp  vital- 
ity is  one  of  those  things  which,  being  well  known  of,  is 
little  knoivn  about. 


10  PREFACE 

Second,  the  necessity  of  acquiring  knowledge  of  correct 
technic:  Dentists  seem  actually  to  consider  it  beneath 
tlieir  dignity  to  try  to  learn  how  to  apply  the  electric 
test  well-.  They  say,  "Why  all  there  is  to  it  is  to  touch 
the  tooth,  and  if  it  hurts  it  is  alive,  and  if  it  doesn't  it  is 
dead.    Isn  't  that  right  ? ' ' 

I  believe  it  requires  more  skill  and  judgment  to  apply 
the  electric  test  correctly  than  to  make  photographically 
good  radiographs.  (Please  note  that  I  say  "photo- 
graphically good  radiographs."  Do  not  misunderstand 
me  to  mean  a  good  radiographic  diagnosis.) 

The  present  attitude  towards  the  electric  test  (and  the 
radiograph,  too,  for  that  matter)  reminds  me  of  the  his- 
tory of  amalgam,  vulcanized  rubber  plates,  and  the  inlay. 

When  amalgam  was  first  introduced  the  curbstone  de- 
scription of  the  technic  for  using  it  ran  something  like 
this :  ' '  You  simply  take  some  filings  in  your  hand,  add  a 
few  drops  of  mercury,  and  rub  them  together  with  your 
thumb.  The  stuff  gets  like  putty,  and  you  daub  it  into 
the  cavity." 

When  rubber  for  plates  was  discovered  it  made  denture 
making  so  easy  a  halfwit  could  do  it — or  did  it  1 

When  the  inlay  appeared,  all. there  was  to  it  was  to 
"punch  a  little  soft  wax  into  the  cavity,  have  the  patient 
bite,  trim  off  the  excess,  pull  it  out,  and  dismiss  the  pa- 
tient." The  next  day  the  patient  came  back  and  the 
inlay  was  slipped  into  place  (??). 

Time  has  caused  us  to  alter  our  opinion  of  these  things. 
But  we  are  going  right  ahead,  making  the  same  mistakes 
about  the  simplicity  of  making  radiographs  and  the  sim- 
plicity of  applying  the  electric  test  for  pulp  vitality.  The 
truth  of  the  matter  is,  or  so  it  seems  to  me,  that  it  is  ex- 
tremely easy  to  do  a  thing  badly  but  hardly  ever  easy  to 
do  it  well. 

There  are  details  about  the  technic  of  doing  most  any- 
thing which  must  be  learned  by  personal  experience. 


PKEFACE  11 

However,  the  personal  experience  of  another  may  make 
your  task  of  developing  technic  much  easier.  My  per- 
sonal experience  in  the  application  of  the  electric  test 
has  been  rather  extensive.  I  have  traveled  from  the 
point  where  I  considered  the  use  of  the  test  absurdly 
simple  to  the  point  where  I  know  it  is  not  so  simple  as  it 
looks,  at  first  sight.  I  hope  I  blaze  the  trail  and  make  the 
going  a  bit  easier  for  those  who  read  this  little  mono- 
graph. 

Third,  the  dental  electrodes  in  use  are  inadequate:  It 
is  little  wonder  that  the  test  is  not  more  popular,  and 
that  some  men  have  started  to  use  it,  only  to  discard  it. 
Most  of  the  dental  electrodes  I  have  seen  in  use  are  such 
as  to  render  the  correct  application  of  the  test  either  ex- 
tremely difficult  or  absolutely  impossible.  In  this  con- 
nection I  may  say  that  I  have  never  kno^^ai  any  one,  who 
has  taken  the  time  to  master  the  technic,  to  discontinue 
the  use  of  the  test. 

Though  I  find  myself  in  rather  extensive  disagreement 
with  what  he  has  written,  I  want  to  direct  attention  to  the 
fact  that  the  first  man  to  have  even  an  inkling  of  the  real 
importance  and  size  of  the  subject  of  electro-diagnosis  of 
pulp  vitality  was  Dr.  Herman  Prinz.  Dr.  Prinz,  years 
ago,  devoted  a  chapter  of  several  pages  to  the  subject 
in  his  book  on  therapeutics.  Upon  reading  it  at  the  time 
I  recall  my  tendency  to  ridicule  Dr.  Prinz 's  efforts  and  to 
accuse  him,  in  my  mind,  of  having  an  inordinate  lot  to  say 
about  a  subject,  which,  as  I  thought  then,  should  have 
been  covered  in  a  few  paragraphs.  In  making  this  ad- 
mission I  automatically  apologize  to  Dr.  Prinz,  and  give 
him  credit  for  his  foresight. 

Now  I  find  myself  writing  a  whole  book  on  the  subject! 
I  have  tried  to  make  the  book  as  short  as  possible  and 
still  have  it  cover  the  subject  in  a  thorough  manner.  Read 
it,  and  see  whether  you  do  not  come  to  the  same  conclusion 
I  have  finally  reached,  wliich  is,  simply  that  tJie  subject  is 


12  PREFACE 

a  bigger  one  than  ive  gave  it  credit  for  being.  I  direct 
your  attention  to  the  fact  that,  in  order  to  keep  the  book 
as  small  as  possible,  I  have  included  no  history,  neither 
have  I  been  able  on  this  account — the  effort  to  keep  the 
book  small — to  include  anything  even  remotely  ap- 
proaching a  detailed  electrical  description  of  the  various 
types  of  pulp  testing  machines. 

To  the  beginner,  particularly,  I  would  say  one  should 
not  attempt  to  ingest,  digest,  and  assimilate  the  subject  at 
one  sitting.  Don't  study  it,  just  read  the  book  from  be- 
ginning to  end.  Then  commence  the  work,  and  study  the 
book  by  referring  to  it  as  you  progress  with  the  work. 

If  after  starting  to  use  the  electric  test  you  are  about 
to  discard  it,  I  earnestly  advise  you  not  to.  Try  again, 
for,  like  the  radiograph,  the  electric  test  for  pulp  vitality 
is  with  us  to  stay.  Electro-determination  of  pulp  vitality 
is  as  essential  to  dental  diagnosis  as  airplanes  are  to 
modern  Avarf  are. 

Even  after  an  author  has  seen  good  proofs,  and  there- 
fore knows  that  good  halftone  plates  have  been  made  for 
his  radiographic  illustrations,  he  cannot  be  sure  that  the 
inl?:  pictures  will  appear  in  his  book  or  his  magazine  ar- 
ticle as  they  appeared  in  the  proof.  What  the  printer 
will  do  to  one's  illustration,  as  this  last  step  in  their  mak- 
ing is  taken,  is  a  matter  of  great  uncertainty. 

I  have  done  more  retouching  in  this  work  than  I  have 
ever  done  before.  Even  so,  I  have  not  done  a  great 
deal.  When  my  first  work  on  Eadiodontia  was  printed 
I  did  not  dare  do  much  retouching.  My  readers  would 
not  have  accepted  my  radiographs  as  true  had  I  done  so. 
Today,  however,  the  profession  as  a  Avhole  has  become 
sufficiently  familiar  with  x-ray  findings  so  that  an  author 
need  not  be  so  careful  to  protect  himself  against  unjusti- 
fiable incredulity. 


PREFACE  13 

TJie  blacks  and  whites  of  ''negative  halftone "  illustra- 
tions are  the  same  as  in  the  original  negative.  The  blacks 
and  whites  of  "print  halftone"  illustrations  are  the  same 
as  in  a  photographic  .print  made  from  the  original  neg- 
ative. Both  have  their  advantages  and  disadvantages. 
The  "'print  halftone"  can  be  made  to  carry  more  detail 
but  the  "negative  halftone"  looks  better  and  can  be  re- 
touched to  better  advantage. 

Of  course  it  is  imiDossible  to  laiow  what  the  future 
holds.  The  electric  test  for  pulp  vitality  has  sufficient 
virtues  so  that  it  should  become  popular,  but  there  are 
some  things  that  react  against  it.  All  of  the  many  de- 
tails necessary  to  its  really  intelligent  use  are  set  forth  in 
Chapters  V,  VI,  VII  and  VIII,  for  example.  But  then 
there  is  this  to  be  said :  Lil^e  the  amalgam  filling  and  the 
radiograph,  it  may  be  used  in  a  very  inadept  manner  and 
still  some  good  results  will  accrue. 

Men  who  find  dental  x-ray  diagnosis  very  easy  will  not 
welcome  the  idea  that  pulp  testing  is  necessary,  for  it 
will  make  their  work  harder  for  them.  But  men  whose 
ambition  it  is  to  make  a  correct  diagnosis  even  if  it  does 
require  work  will  welcome  the  test. 

The  "Analysis  of  the  Book  for  the  Benefit  of  the  Busy 
Reader"  will,  I  hope,  meet  with  the  approval  of  "the 
Busy  Reader."  The  effort  is  something  of  an  innovation, 
as  far  as  I  know.  It  is  i^rompted  by  a  desire  to  do  unto 
my  reader  as  I  would  wish  to  be  done  by. 

I  am  glad  to  show  my  appreciation,  by  acknowledging 
my  indebtedness  and  offering  my  formal  thanks  to  Mrs. 
H.  R.  R.,  who  has  done  most  of  the  literary  work  (includ- 
ing the  exasperating  task  of  proof  reading)  which  lies  be- 
tween the  first  "dirty  copy"  and  the  finished  book. 

H.  R.  R. 

Albuquerque  and  IndiaiiaxJolis. 


CONTENTS 


Chapter  I 
By  Way  of  a  Beginning 19 

Chaptee  II 
Pulp    Testing    Machines 23 

Chapter  III 
Eequisites   of   a   Pulp   Testing   Outfit 35 

Chapter  IV 
Funcfamentals  in  Teclinic  of  Apx^lying  Electric  Test 45 

CilAPTER  V 
Special  Points  in   Technie 50 

Chapter  VI 
Things  Which  Modify  the  Strength  of  Current  Necessary  to  Test  Teeth     75 

Chapter  VII 
Limitations 83 

Chapter  VIII 
Applying  the  Test  for  Nervous  Patients 86 

Chapter  IX 
Answering  Adverse  Criticism 91 

Chapter  X 
Clinical  Value  of  the  Test 95 

Chapter  XI 
The  Test  as  an  Aid  in  the  Interpretation  of  Eadiographs 108 


14 


ILLUSTRATIONS 


FIG.  PAGE 

1.  Unsightly   Faradic   outfit 25 

2.  Neat  appearing  Faradic  machine 27 

3.  A   very    elaborate    and    expensive    type    of    galvanic    and    Faradic 

machine 27 

4.  A  modified  Faradic  machine 28 

5.  An  ionization  machine    (on   dental   bracket) 30 

6.  Pulp  tester  of  the  type  which  operates  from  a  lamp  socket     ...  31 

7.  High-frequency    machine 32 

8.  Tip  or  plug 35 

9.  Showing  how   some   tips   separate   so   a  broken   cord   may   be   re- 

paired        35 

10,  11,  and  12.     Wrong  types  of  dental  electrodes 37 

33.  A  combination  current  controller  and  dental  electrode 38 

14.  The   right  kind   of   dental   electrode 39 

15.  The  common  type  of  hand  electrode 40 

16.  Hand  electrode  of  special  design 40 

17.  A  type  of  indifferent  electrode  which  clamps  on  the  cheek     ...  40 

18.  Cotton  holder  with  ring  of  blotting  paper  about  base 41 

19.  Small   medicine    dish 41 

20.  Dental    mouth    mirror 41 

21.  Dental  cotton  tweezers 41 

22.  Eecord  blank  to  record  results  of  the  applications  of  the  electric 

test  for  pulp  vitality 43 

23.  Special  Faradic  type  pulp  tester  with  parts  labeled 46 

24.  Moisture  contact,  not  actual  contact 51^ 

25.  How  cotton  should  be  wrapped  on  the  dental  "electrode     ....  53 

26.  Wrong  way  to  wrap  the  dental  electrode  with  cotton 53 

27.  Touching  tooth  with  the  end   of  the   electrode 55 

28.  Electrode  laid  against  surface  of  tooth 56 

29.  Showing  where  and  why  cords  wear  out  and  break 60 

SO.  Applying  the  electrode  to  the  labial  surface  of  an  upper  anterior 

tooth 63 

31.  Applying  the  electrode  to  the  lingual  surface  of  an  upper  anterior 

tooth 64 

32.  Applying  the  electrode  to  the  buccal  surface  of  an  upper  left  pos- 

terior  tooth ^^ 

33.  Applying  the  electrode  to  the  lingual  surface  of  an  upper  left  pos- 

terior  tooth ^^ 

15 


16  ILLUSTRATIONS 

riG.  PAGE 

34.  Applying  the   electrode  to   the   buccal   surface   of   an  upper   right 

posterior  tooth 67 

35.  Applying  the  electrode  to   the   lingual  surface   of  an  upper  right 

posterior  tooth 68 

36.  Applying  the   electrode   to   the  labial   surface   of  a  lower   anterior 

tooth 69 

37.  Applying  the  electrode  to  the  lingual  surface  of  a  lower  anterior 

tooth 70 

38.  Applying  the  electrode  to  the  buccal  surface  of  a  lower  left  pos- 

terior  tooth 71 

39.  Applying  the  electrode  to  the  lingual  surface  of  a  lower  left  pos- 

terior  tooth 72 

40.  Applying  the  electrode  to  the  buccal  surface  of  a  lower  right  pos- 

terior  tooth 73 

41.  Applying  the  electrode  to  the  lingual  surface  of  a  lower  right  pos- 

terior  tooth 74 

42.  In  some  cases  it  may   be   expedient  to  make  an   opening  through 

the  enamel  to  apply  the  dental  electrode 77 

43-135.  Eadiographs 109-153 


ANALYSIS  OF  THE  BOOK  FOR  THE  BENEFIT  OF 
THE  BUSY  READER 


CHAPTER  I 

By  Way  of  a  Beginning 
A  short  chapter  in  which  the  writer  sets  forth  some  of  his  views  regard- 
ing the  electric  test  for  pulp  vitality.     Of  passing  interest. 

CHAPTER  II 
Pulp  Testing  Macpiines 
In  which  tlie  various  types  of  pulp  testing  machines  are  mentioned  and 
their    relative    advantages   and    disadvantages    discussed.      Not    much    said 
about  electric  construction. 

CHAPTER  III 

Requisites  of  a  Pulp  Testing  Outfit 

In  which  the  requisites  of  a  pulp  testing  outfit  are  enumerated  and 
discussed.  Special  emphasis  being  laid  on  the  necessity  of  using  the  right 
land  of  a  dental  electrode. 

CHAPTER  IV 
Fundamentals  in  the  Technic  of  Applying 
The  Electric  Test  foe  Pulp  Vitality 
Only  the  barest   fundamentals   in  the   technic   of   applying   the   electric 
test  for  pulp  vitality  are   set   forth  in  this   chapter.      The   operator  must 
have  the  knowledge  set  fortli  in  this  chapter  or  he  cannot  apply  the  test 
at  all. 

CHAPTER  V 

Special  Points  in  Technic 
Wherein  special  points  iu  technic  are  described.     This  is  a  very  impor- 
tant   chapter.      The    operator   need    have    only   the    information    set    forth 
in  Chapter  IV  to  apply  the  test,  but  if  he  would  apply  it  well,  he  must 
master  the  special  points  in  technic   set  forth  in  this  chapter. 

CHAPTER  VI 

Things  Which  Modify  the  Strength  of 
Current  Necessary  to  Test  Teeth 
Like    Chapter    V,    this    is    an    important    chapter.      Tlie    information    it 
gives  is  necessary  to  an  intelligent  use  of  the  test. 

17 


18  ANALYSIS  OF  BOOK 

CHAP  TEE  VII 

Limitations  of  the  Test 
All  tests,  no  matter  how  good,  have  limitations,  and  it  is  as  necessary  to 
know  the  limitations  of  a  test  as  well  as  the  possibilities,  and  so  guard 
against  disappointment  and  error. 

CHAP  TEE  VIII 
Applying  the  Test  for  Nervous  Patients 
A   sort   of   verbal   clinic   in   which   the   writer   attempts   to    describe   in 
detail  how  he  handles  nervous  patients. 

CHAPTEE  IX 

Answering  Adverse  Criticism 

Not   a   great   deal  has   been   written   about   the    electric   test   for  pulp 

vitality  but  that  which  has  appeared  seems  to  have  been  either  definitely 

laudatory  or  definitely  derogatory.      The  writer  has  already  discussed  the 

limitations  of  the  test  and  here  answers  criticisms  which  seem  to  him  unjust. 

CHAPTEE  X 

Clinical  Value  of  the  Test 
A  chapter  to  be  browsed  over.     An  effort  to  indicate  the  clinical  value 
of  the  test  verbally. 

CHAPTEE  XI 
The  Test  As  An  Aid  in  the  Interpretation  of  Eadiographs 
(Cases  from  Practice) 
An   effort   to   prove   the   value   of   the   test   by   submitting   considerable 
radiographic  evidence  of  its  necessity  to  the  correct  interpretation  of  radio- 
graphs.    Perhaps  the  most  important  chapter  in  the  book. 


ELECTRO -RADIOGRAPHIC  DIAGNOSIS 


CHAPTER  I 

BY  WAY  OF  A  BEGINNING 

There  is  no  incentive  to  study  the  always  more  or  less 
dull  subject  of  technic  unless  one  is  aware  of  the  benefits 
to  be  derived.  So,  my  reader,  if  you  are  not  already  cog- 
nizant of  the  importance  of  the  electric  test  for  pulp 
vitality  as  a  diagnostic  measure,  perhaps  you  should 
read  the  last  two  chapters  first.  It  may  give  you  more 
enthusiasm  for  the  task  of  mastering  technic.  And  re- 
member, results  depend  on  technic;  poor  technic,  xDoor 
results. 

Why  We  Test  Teeth  for  Pulp  Vitality 

It  is  so  nearly  correct  that  it  is  ciuibbling  to  dispute 
the  statement  that  a  tooth  with  a  vital  pulp  is  never  ab- 
scessed— i.  e.,  never  a  source  of  periapical  infection — 
Avhile  the  tooth  without  a  vital  pulp  may  be  abscessed. 
Hence  the  necessity  in  the  practice  of  dentistry  and  radio- 
dontia  of  determining  pul^D  vitality. 

I  have  never  encountered  a  case  of  periapical  abscess 
of  a  tooth  with  a  vital  pulp.*  Those  cases  which  have 
been  brought  to  my  attention  by  others  have  all  seemed 
to  me  to  be  mistakes  in  diagnosis. 

For  example,  a  man  shows  me  a  radiograph  in  which 
two  ai^proximating  teeth  seem  to  be  involved  in  an  ab- 
scess and  says,  "One  of  those  teeth  had  a  vital  pulp. 
There's  a  case  of  abscess  at  the  ajoex  of  a  vital  tooth." 


*I  am  not  considering  here  multirooted  teeth  with  the  pulp  in  one  canal  dead 
and  septic  and  an  abscess  at  the  apex  of  the  root  while  the  pulp  in  another  canal 
remains  vital  or   semi-vital. 

19 


20  ELECTRO-KADIOGRAPHIC    DIAGNOSIS 

His  clisagreeiiient  and  mine  arises  from  the  fact  that  he 
accepts  what  the  radiograph  seems  to  show  without  ques- 
tion, without  taking  into  account  the  fact  that  the  angle 
at  which  the  radiograph  was  made  may  have  been  such  as 
to  cause  an  overlapping  of  a  root  end  and  an  abscess 
cavity  which  have  no  actual  connection  with  one  another, 
or  that  the  abscess  cavity  may  lap  to  the  lingual  of  the 
tooth  with  the  vital  pulp  without  involving  its  apex. 

It  is  a  homely  comparison  but  it  expresses  my  view  of 
the  matter  to  say  that  a  hose  or  rope  cannot  pass  through 
a  bonfire  without  being  burned  in  two.  Neither  can  blood 
vessels  and  nerves  pass  through  an  abscess  to  enter  a 
tooth  without  being  '^ burned"  in  two. 

Electric  Test  Compared  to  Other  Tests 

No  test  for  pulp  vitality,  other  than  that  of  making  a 
diagnostic  opening  into  the  tooth,  is  infallible — not  even 
the  electric  test.  But  the  electric  test  is  so  far  superior 
to  all  others  that  it  should  be,  and  is  coming  to  be,  used 
by  all  dentists  and  dental  radiographers.  Carried  to  its 
logical  conclusion — to  the  point  of  sensitivity  or  into  the 
pulp  cavity — the  procedure  of  making  a  diagnostic  open- 
ning  into  a  tooth  is  absolutely  reliable  as  a  means  of  de- 
termining pulp  vitality.  But  this  procedure  of  opening 
the  tooth  is  the  very  thing  we  wish  to  avoid  if  possible. 

To  avoid  the  necessity  of  opening  teeth  to  determine 
pulp  vitality,  thermal  tests,  transillumination  tests,  and 
palpation  tests  are  as  inadequate,  when  compared  to  the 
electric  test,  as  the  old  hand  excavating  instruments  com- 
pared to  the  modern  dental  engine. 

''Too  Rosy" 

While  the  writer  fully  appreciates  the  merits  of  the 
electric  test  for  pulp  vitality  and  counts  the  test  a  neces- 
sity for  dentists  and  radiodontists,  it  would  seem  wise, 
however,  to  give  a  word  of  warning. 


BY   WAY    OF   A    BEGHSTNING  21 

Enthusiasts  say  tilings  like  this  about  the  test:  ''Abso- 
lutely painless,"  ''Absolutely  reliable,"  "So  simple  the 
technic  of  its  use  can  be  mastered  in  a  few  moments," 
"Enables  the  operator  to  locate  devitalized  teeth  speed- 
ily and  without  fail, "  "If  you  fail  to  get  a  reaction  from 
this  test  it  is  quite  certain  the  pulp  is  devitalized." 

There  is  good  foundation  for  such  remarks  as  tlije  fore- 
going, and  yet  they  are  very  misleading;  they  are  too 
rosy.  They  lead  men  to  expect  too  much.  "Absolutely 
reliable  "  is  a  very  dangerous  thing  to  say  about  any  test. 

Pulp  Devitalization  Due  to  Application  of  the  Test 

Just  having  remarked  on  the  care  one  should  exercise 
when  using  that  very  uncompromising  word  ' '  absolutely" 
the  writer  feels  he  is  exercising  necessary  care  and  is 
justified  in  using  it  and  saying  that,  so  far  as  danger  of 
devitalization  of  the  ]Dulp  is  concerned,  the  test  is  ab- 
solutely safe.  As  I  make  this  statement  I  have  in  mind 
the  use  of  the  Faradic  type  of  pulp  testing  machine.  Per- 
haps the  other  types  are  just  as  safe,  but  I  do  not  kiioiv  it 
to  be  a  fact  from  experience  as  I  know  of  the  safety  of  the 
Faradic  machine. 

Advantages  of  the  Test 

The  advantages  derived  from  using  the  electric  test 
for  pulp  vitality,  in  connection  with  radiographic  exam- 
ination, are:  (1)  Misinterpretation  of  radiographs  is 
much  less  likeh^  to  occur.  (2)  The  application  of  the  test 
enables  the  operator  to  select  those  teeth  which  should  be 
radiographed  with  especial  care.  (3)  Because  it  assists 
in  radiographic  interpretation  and  because  it  points  out 
the  particularly  suspicious  teeth,  the  test  reduces  the 
number  of  exposures  necessary,  particularly  the  number 
of  make-overs  necessary.  (This  is  especially  advanta- 
geous to  the  conscientious  operator.)    (4)  When,  in  a  case 


22  ELECTRO -RADIOGRAPHIC    DIAGNOSIS 

of  metastatic  infection  the  patient  cannot  afford  to  have 
all  parts  of  the  month  radiographed,  the  number  of  radio- 
graphs made,  and  so  the  cost,  can  be  reduced  to  a  mini- 
mum by  eliminating  those  teeth  from  examination  which 
respond  perfectly  to  the  electric  test  for  pulp  vitality. 
(5)  Carelessly  used,  x-rays  are  dangerous.  An  x-ray 
tube  should  never  be  lighted  unnecessarily.  Th'fe  use  of 
the  test  lessens  exposure  of  both  patient  and  operator. 


CHAPTER  II 
PULP  TESTING  MACHINES 

The  Source  of  the  Current 

To  apply  the  electric  test  for  pulp  vitality  we  must  have 
an  electric  current  of  the  proper  nature,  i.e.,  a  current  of 
the  correct  voltage,  amperage  and  character.  The  or- 
dinary commercial  current,  as  supplied,  cannot  be  used. 
The  commercial  current  may  be  passed  through  an  elec- 
tric machine  and  modified  to  meet  the  requisites  of  a 
current  suitable  for  testing  pulps  for  vitality. 

Likewise  the  current  of  a  drj^  cell  may  be  passed 
through  an  electric  machine  and  so  modified  to  conform 
to  the  requisites  of  a  current  suitable  for  testing  pulps. 

Types  of  Pulp  Testing  Machines 

The  following  are  types  of  machines  used  as  pulp  test- 
ers, named  somewhat  in  the  order  of  their  popularity. 
The  first  and  last  ones  named  derive  their  current  from 
dry  cells  (batteries)  while  the  others  operate  on  the  com- 
mercial circuit.  (1)  The  Faradic  machine.  (2)  The  ion- 
ization machine.  (3)  The  dental  switchboard.  (4)  The 
choke  coil  or  rheostat,  or  transformer.  (5)  The  high- 
frequency  machine.  (Also  known  as  the  Tesla  coil  and 
"violet  ray  machine.")  (6)  A  flashlight  battery  ma- 
chine. 

The  Faradic  Machine 

As  its  place  in  the  list  of  pulp  testing  machines  indi- 
cates, the  most  extensively-used  type  of  pulp  tester  is  the 
Faradic  machine.     Ever^'-thing  considered,  i.e.,  safety, 

23 


24  ELECTRO-EADIOGRAPHIC    DIAGNOSIS 

transportability,  ease  in  handling,  comparatively  low 
cost,  and  high  efficiency — its  popularity  is  entirely  mer- 
ited. 

The  Parts  of  a  Faradic  Machine 

The  essential  parts  of  a  Faradic  machine  are:  a  dry 
cell,  an  interrupter,  and  a  coil. 

Tracing  the  Current  Through  the  Machine 

From  the  cell  the  current  passes  through  a  mechanical 
interrupter  (Fig.  2)  and  thence  to  a  little  step-up  tran^*- 
f ormer  or  coil,  by  means  of  which  the  current  of  compar- 
atively high  amperage  (quantity)  and  low  voltage  (pres- 
sure), from  the  cell,  is  transformed  into  a  current  of 
comparatively  low"  amperage  (quantity)  and  high  voltage 
(pressure).  It  is  also  changed  from  a  direct  current  to 
an  alternating  current. 

Safety 

A  machine  which  generates  its  own  current,  so  to  speak, 
like  the  Faradic  machine,  has  some  advantages  over  any 
switchboard  attachment  or  any  machine  deriving  its  elec- 
tricity from  some  powerful  source  of  supply.  In  case  of 
accident  or  misuse  no  serious  results  can  occur,  for  the 
perfectly  apparent  reason  that  the  current  generated 
from  one  commercial  dry  cell  cannot  be  strong  enough  to 
be  dangerous.  This  should  appeal  to  any  one,  but  par- 
ticularly to  men  whose  knowledge  of  electricity  is  limited. 

The  manufacturer  of  a  pulp  testing  machine  which 
operates  by  connection  to  a  light  socket  directs  attention 
to  the  humming  noise  produced  by  the  Faradic  machine 
and  claims  the  noise  may  frighten  patients.  If  one  would 
be  just,  it  is  necessary  to  concede  the  fairness  of  the 
criticism.    However,  which,  may  I  ask,  is  more  likely  to 


PULP    TESTIISTG    MACHINES 


25 


frighten  the  patient,  tlie  hnm  of  the  Faradic  machine  or 
the  sight  of  an  electric  machine,  one  end  of  which  is  at- 
tached to  a  light  socket  and  the  other  end  about  to  be 
introduced  into  the  patient 's  mouth  f 

To  carry  the  picture  still  further  the  operator,  having 
a  machine  attached  to  a  lamp  socket,  now  moves  the  pa- 


■Unsiglitly   Faradic   outfit. 


tient's  arm  from  where  it  touches  the  metal  trimming  of 
the  fountain  cuspidor  with  the  solenm  warning,  "You 
mustn't  be  in  contact  with  any  metal  when  I  apply  this 
test."    Does  the  patient  now  feel  perfectly  secure? 

AVhen  the  Faradic  machine  is  used,  contact  with  metal 
cannot  possibly  result  in  any  accident. 


26  ELECTKO-RADIOGRAPHIC    DIAGl^TOSIS 

Transportability 

The  machine  that  generates  its  own  current  from  a 
commercial  dry  cell  depends  only  on  the  cell  and,  with  the 
cell  supplied,  will  operate  any  time,  anywhere,  and  with- 
out variation.  It  can  be  moved  from  place  to  place  in 
the  office,  or  from  place  to  place  anywhere  on  the  face  of 
the  earth  for  that  matter.  The  absence  of  a  cord,  con- 
nected to  a  light  socket,  which  is  everlastingly  upsetting 
something  or  other  on  one's  bracket  or  cabinet,  increases 
the  comfort  with  which  one  moves  the  machine  in  the 
position  for  use,  then  out  of  the  way  again. 

The  ordinary  dry  cell  can  be  obtained  anywhere  in  the 
civilized  world.  A  cell  will  give  service  for  about  one 
year,  when  it  may  be  replaced  very  easily  at  a  small  cost. 

The  Appearance  of  Faradic  Machines 

Commercial  Faradic  machines,  as  found  on  the  market, 
vary  greatly  in  appearance.  Some  are  unsightly  and 
awkward  to  handle,  especially  those  in  which  the  cell  and 
coil  are  not  mounted  together,  but  are  separate  with  only 
wire  connections.  (Fig.  1.)  Others  are  ordinary  look- 
ing. Some  are  rather  attractive.  (Fig.  2.)  Still  others 
are  very  elaborate  in  appearance.  (Fig.  3.)  Most  of 
them  may  be  recognized  by  the  patient  as  what  is  collo- 
quially designated  a  "shocking machine."  This  is  a  dis- 
advantage, for  when  it  is  recognized  as  a  shocking  ma- 
chine, some  patients  are  more  reluctant  to  submit  to  its 
use.  Perhaps  they  remember  its  sting,  or  perhaps  it  is  be- 
cause they  do  not  appreciate,  or  may  even  hold  in  con- 
tempt, anything  which  is  familiar  to  them. 

An  Effort  and  a  Failure 

Though  the  Faradic  machine  makes  a  good  pulp  tester, 
it  is  not  with^t  its  shortcomings.  Some  years  ago,  in 
1917,  to  be  exact,  I  endeavored  to  produce  a  pulp  testing 


PULP   TESTING    MACHHsTES 


27 


machine  of  the  Faradic  type  which  would  have  the  fol- 
lowing improvements  over  the  ordinary  commercial 
Faradic  machine:  (1)  It  was  to  have  the  right  kind  of  a 


INTERRUPTER 


COIL 


-V-.    SLIDING 
SHEATH 


Fig.  2. — Neat  appearing  Faradic  machine. 


Fig.   3. — A  very   elaborate   and  expensive  type  of   galvanic  and   Faradic   machine. 


dental  electrode.  (2)  It  Avas  to  he  a  neater,  better  looking 
outfit.  (3)  It  was  to  have  an  appearance  that  would  not 
remind  the  patient  of  the  familiar  "^shocking  machine." 


28  ELECTRO-EADIOGEAPHIC    DIAGJSTOSIS 

(4)  It  was  to  have  a  better  control  of  the  output  current. 

(5)  It  was  to  make  less  noise.     (6)  It  was  to  cost  only  a 
little  more  than  the  ordinary  Faradic  machine. 

After  much  trouble  the  machine  shown  in  Fig.  4  was 
produced.  Of  the  six  objectives  just  given,  only  the  first 
three  were  attained.  The  dental  electrode  was  all  one 
could  desire ;  the  outfit  was  really  attractive ;  and  it  in  no 
way  resembled  the  old  ' '  shocking  machine. ' '  There  was 
no  improvement  whatever  in  the  control  of  the  output 
current  over  the  controls  on  the  ordinary  Faradic  ma- 


Fig.  4. — A  modified  Faradic  machine. 

chine;  it  made  more,  instead  of  less,  noise,  and,  owing  to 
the  increased  cost  of  everything  due  to  the  war,  its  selling 
price  was  high.  As  though  this  were  not  enough,  the 
machine  harbored  a  serious,  inexcusable  mechanical  de- 
fect. As  soon  as  I  directed  attention  to  the  serious  faults 
of  the  pulp  tester,  it  was  promx^tl}^  withdrawn  from  the 
market. 

A  Defect  of  Faradic  Machines  and  How  to  Overcome  It 

Ionization  machines  and  the   expensive  pulp  testing 
machines  which  operate  from  lamp  sockets,  have  a  single 


PULP    TESTIXG    MACHINES  29 

current  controller  wliicli  grades  the  output  current  from 
zero,  or  approximately  zero,  to  the  maximum  strengtli 
needed,  while  the  output  current  of  the  ordinary  com- 
mercial Faradic  machine  is  regulated  in  two  ways:  One, 
by  the  manner  of  attaching  the  electrodes  to  the  machine, 
the  other  by  a  cylinder  controller,  i.e.,  the  sliding  sheath 
or  tube,  which  increases  the  current  strength  as  it  is 
pulled  out.  (Fig.  2.)  To  cope  with  this  shortcoming 
of  having  to  change  plugs,  I  have  developed  a  stratagem 
or  '^ stunt"  in  technic,  (see  Chapter  V  under  the  heading 
"A  Valuable  Point  in  Technic")  which  meets  the  situa- 
tion and  overcomes  its  difficulties,  on  most  machines. 
It  must  be  admitted,  however,  that  there  are  some 
Faradic  machines  which  are  controlled  so  imjDerfectly 
by  their  sliding  sheaths  that  they  are  not  amenable 
to  any  stratagem  and  so  make  poor  pulp  testers.  I 
should  make  it  clear  that  it  is  not  the  fact  that  there  are 
two  modes  of  control  which  are  especially  objectionable, 
but  the  objection  is  to  the  nature  of  one  of  the  controls ; 
that  is,  the  objection  is  to  the  necessity  of  changing  un- 
insulated plugs  from  one  socket  into  another. 

However,  one  cannot  gainsay  the  fact,  it  is  easier  to 
operate  a  machine  which  operates  from  a  single  control 
and  grades  from  zero  or  ajoproximate  zero  upward.  Some 
of  the  more  expensive  Faradic  machines  are  equipped 
Avith  '^ choke  coils"  or  rheostats  instead  of  the  sliding 
sheath.  Such  machines  admit  of  a  more  perfect  control 
of  the  output  current. 

Another  Effort 

Though  I  failed  so  utterly  in  my  first  effort  to  have  an 
ideal  pulp  tester  made  of  a  Faradic  machine,  the  failure 
was  due  entirel^^  to  preventable  mistakes  and  such  an 
ideal  pulp  tester,  I  am  promised,  is  now  being  produced 
bv  another  manufacturer. 


30  •  ELECTRO-EADIOGRAPHIC    DIAGNOSIS 

The  Ionization  Machine 

Equipped  with  the  right  kind  of  a  dental  electrode 
(Fig.  14)  some  ionization  machines  (Fig.  5)  make  ade- 
quate pulp  testing  machines.  An  ionization  machine 
should  not  be  purchased  if  it  is  to  be  used  only  as  a 
pulp  testing  machine,  for  a  good  pulp  testing  machine  of 
a  different  style,  say  the  Faradic  type,  can  be  purchased 


Fig.    5. — An   ionization   machine    (on   dental   bracket). 

at  much  less  expense.  If,  however,  one  intends  to  use,  or 
is  using  ionization,  then  the  ionization  machine  may  be 
used  as  a  pulp  tester  if  the  current  it  generates  is  strong 
enough. 

The  Dental  Switchboard 

Some  dental  switchboards  are,  I  understand,  now  made 
with  sockets  (places  for  attachment)  where  a  suitable 
current  for  pulp  testing  may  be  obtained.    If  the  switch- 


PULP    TESTIXG    IMACHIXES  31 

board  lias  been  built  witli  the  idea  of  giving  tlie  operator 
a  pulp  testing  current,  doubtless  such  a  current  is  avail- 
able, for  dentistr^^  is  fortunate  in  having  such  reliable 
manufacturers  of  electric  equipment.  But  certainly  it  is 
"risky  business"  to  "tap"  somewhere  into  a  switch- 
board, not  built  especially  to  deliver  a  pulp  testing  or 
ionization  current  in  the  hoioe  that  the  current  attained 
will  be  of  the  right  character. 

As  always,  when  using  the  dental  switchboard  as  a 
pulp  tester,  one  must  use  the  right  kind  of  dental  elec- 
trode, or  failure  will  result  no  matter  how  joerfect  the 
current  supplied  may  be. 

The  Choke  Coil,  Rheostat  or  Transformer 

The  machine  I  designate  as  a  choke  coil,  rheostat,  or 
transformer  (Fig.  6)  operates  from  a  lamjD  socket.  As 
the  name  implies,  the  commercial  current  taken  from  the 
light  socket  is  choked  back  or  altered  by  means  of  a 
transformer  coil  and  delivered  by  the  machine  for  use  in 
the  correct  strength  to  test  pulps. 


Fig.   6. — Pulp   tester   of  the  type  which  operates   from  a  lamp   socket. 

The  necessity  of  connecting  this  little  machine  to  a 
light  socket  is  disadvantageous  and  sometimes  amioying. 
However,  these  things  are  not  vital  to  the  efficiency  of 
the  machine  as  an  adequate  iDulp  tester. 


32 


ELECTEO-EADIOGRAPHIC    DIAGNOSIS 


The  High- Frequency  Machine 

(Also  known  as  the  Tesla  Coil  and  Violet  Ray  Machine) 

The  high-frequency  machine  (Fig.  7)  is  used  by  some 
as  a  pulj)  tester.  Perhaps  the  best  wa,y  to  express  its 
status  as  a  pulp  tester  is  to  say  it  has  undeveloped  possi- 
bilities. The  fact  that  the  high-frequency  current  may 
be  applied  to  metal  fillings  and  crowns  without  extreme 
pain  is  an  advantage  but  the  following  shortcomings  are 
serious  disadvantages:  (1)  Ordinary  insulation  does  not 
suffice;   the   current   penetrates   heavy  wire   insulation. 


Fig.    7. — High-frequenc}'   machine.      Also   known   as    Tesla   Coil   and    "Violet   Ray 

Machine." 

Therefore,  the  wire,  or  cord,  must  not  be  allowed  to  come 
in  contact  with  the  patient.  The  patient's  clothing  offers 
no  protection  to  a  current  of  such  an  extreme  penetration. 
The  current  is  not  dangerous  but  it  is  disagreeable,  and 
frightens  patients.  (2)  The  dental  electrodes  are  big  and 
awkward  to  handle — entirely  impractical  in  my  opinion. 
(3)  The  machine  makes  a  distracting  racket.  (4)  Al- 
though a  small  quantity  of  the  current  sparked  into  the 
metal  of  a  filling  or  a  crown  does  not  cause  pain,  a  large 
enough  quantity  will  cause  a  pain  reaction  even  if  the 


PULP    TESTING    MACHINES  oo 

tooth  is  not  vital.    (5)  Tlie  means  of  regulating  the  high- 
frequency  current  is  neither  very  accurate  nor  easy. 

Dr.  Simpson's  Opinion 

I  must  admit  that  I  have  never  used  the  high-frequency 
current  except  experimentally.  That  is  I  have  never  used 
it  in  routine  practice.  Dr.  Clarence  0.  Simpson  has  used 
the  high-frequency  current  for  pulp  testing  for  two  years 
and  so  let  us  see  what  he  has  to  say  about  it.  I  am  in- 
debted to  Dr.  Simpson  for  the  statement  Avhicli  follows : 

"Regarding  the  use  of  the  high-frequency  current  for 
vitality  test,  let  me  preface  the  statement  by  admitting 
that  it  is  not  automatic,  showing  a  plus  or  minus  on  an 
indicator  when  a  tooth  is  touched,  but  some  experience, 
imagination,  and  discrimination  must  be  employed. 
There  is  a  great  difference  in  the  response  from  different 
patients,  but  vitality  can  be  determined  in  most  cases  ex- 
cepting those  of  extreme  pulp  recession  and  crowned 
teeth.  When  a  very  strong  current  is  used  on  a  crown 
or  pulpless  tooth,  it  jumiDS  to  adjacent  teeth  with  that 
possibility  of  error,  but  most  teeth  respond  before  the 
current  is  raised  to  that  degree.  This  difficulty  does  not 
arise  excepting  in  lower  incisors  or  pulp  recession.  In- 
sulation by  rubber  dam  reduces  the  jumping,  but  only  to 
a  limited  degree,  isolation  is  more  accurate  than  insula- 
tion since  high-frequency  current  baffles  all  practicable 
insulation  media.  Some  of  the  advantages  of  high-fre- 
quency for  pulp  testing  are:  A  greater  capacity  than  can 
be  obtained  from  the  usual  faradic  generators,  the  ab- 
sence of  shock  to  the  tongue  and  on  metallic  restorations, 
and  obviation  of  the  necessity  of  the  patient 's  holding  an 
electrode. ' ' 

The  Flashlight  Machine 

Everyone  has  seen  pocket  electric  flashlights  of  all 
kinds:  some  almost  as  small  as  a  fountain  pen,  others 
much  larger  and  giving  a  stronger  light. 


34  ELECTRO-RADIOGRAPHIC    DIAGNOSIS 

The  flash  light  battery  pulp  tester  is  at  the  present  time 
little  more  than  an  idea  in  the  mind  of  one  of  my  friends. 
If  I  am  to  believe  what  I  am  told  (I  have  never  seen  it) 
an  experimental  machine  of  this  type  has  been  made  and 
' '  works  fairly  well. ' ' 

The  principle  of  such  a  machine  does  not  appeal  to  me. 
The  most  important  single  thing  about  a  pulp  testing  out- 
fit is  that  the  dental  electrode  shall  be  right,  shall  be  neat 
and  easy  to  handle.  The  feature  of  the  flash  light  battery 
pulp  tester  is  that  it  shall  be  so  small  a  machine  that  it 
may  be  handled  in  one  hand  and  used  as  a  dental  elec- 
trode. Such  a  machine,  as  a  machine,  may  be  small  and 
neat,  but  as  a  dental  electrode,  it  is  too  big  and  awkward 
to  handle.  For  this  reason,  if  no  other,  I  have  no  enthu- 
siasm for  it. 


CHAPTEE  III 

REQUISITES  OF  A  PULP  TESTING  OUTFIT 

A  pulp  testing  outfit  sliould  consist  of  pulp  testing  ma- 
chine, cords,  dental  electrode,  hand  electrode,  cotton 
holder,  cotton,  piece  of  blotting  paper  or  napkin,  vessel 
to  contain  water  or  saline  solution,  mouth  mirror,  cotton 
tweezers,  blanks  on  which  to  keep  records. 

Pulp  testing  machines  have  already  been  considered  in 
Chapter  11. 

Cords 

The  cords  or  insulated  wires  which  are  used  to  connect 
the  electrodes  to  the  machine  should  be  of  sufficient 
length. 


Fig.   9. — Showing  how   some  tips   separate   so   a  broken   cord  may   be  repaired. 

If  the  tips  or  plugs  (Fig.  8)  on  the  ends  of  the  cords 
are  insulated  instead  of  the  usual  metal  tip,  it  is  advan- 
tageous. When  such  insulated  tips  are  used,  they  may  be 
changed  from  one  socket  to  another  while  the  machine  is 
turned  on  without  danger  of  shocking  the  operator  or 
patient.  (The  metal  tip  may  be  covered  with  adhesive 
tape  to  insulate  if  desired.) 

Cords  not  infrequently  break  just  where  they  enter  the 
tip  or  plug.  Some  cord  tijDS  are  so  made  that  this  break 
may  be  repaired  easily.    (Fig.  9.) 

35 


36  ELECTEO-EADIOGEAPHIC    DIAGNOSIS 

-  The  Active  or  Dental  Electrode 

The  use  of  inadequate  dental  electrodes  has  done  more 
to  discourage  beginners  and  keep  operators  from  realiz- 
ing the  full  benefits  to  be  gained  from  the  test  than  any 
other  thing. 

Take  Figs.  10,  11,  and  12  as  examples  of  the  wrong 
kinds  of  dental  electrodes.  When  using  them  the  oper- 
ator is  constantly  coming  in  contact  with  the  uninsulated 
parts  at  the  base  of  the  electrode;  and  the  patient's  lips, 
cheeks  and  tongue  are  touching  the  uninsulated  parts  at 
the  other  end  of  the  electrode.  When  the  operator's  hand 
touches  the  uninsulated  parts,  he  receives  a  shock  and  if 
his  other — his  left — hand  is  in  contact  with  the  patient  as 
it  usually  is,  resting  against  the  patient's  face  (the  fingers 
holding  a  mouth  mirror  perhaps,  and  the  mirror  in  the 
patient's  mouth)  the  shock  is  transmitted  to  the  patient. 

Fig.  13  is  a  combination  dental  electrode  and  current 
controller.  The  current  strength  is  increased  by  pushing 
in  a  piston  very  much  as  one  pushes  in  the  piston  of  a 
syringe.  This  sort  of  electrode  is  an  awkward  thing  to 
handle,  a  fatal  fault.  The  hand  which  seeks  to  direct  a 
dental  electrode  to  touch  teeth  at  the  right  spot  without 
touching  lips,  cheeks,  tongue,  or  gum,  or  mouth  mirror, 
is  a  busy  hand;  it  should  not  be  called  upon  to  regulate 
the  current  also. 

Since  the  application  of  the  electric  test  has  come  to 
occupy  such  an  important  place  in  the  writer's  radio- 
dontic  practice,  all  sorts  of  dental  electrodes  have  been 
tried.  At  one  time  a  set  of  three  different  electrodes  were 
used  to  reach  the  various  surfaces  of  the  teeth  without 
touching  the  soft  parts.  Finally  the  electrode  shown  in 
Fig.  14  was  designed.  It  is  almost  absurdly  simple,  yet 
it  seems  to  be  precisely  the  right  thing  for  the  use  to 
which  it  is  put.  Those  who  have  used  other  dental  elec- 
trodes or  sets  of  electrodes  like  those  shown  in  Figs.  10, 
11,  and  12,  for  example,  w^ll  share  my  enthusiasm  for  this 
very  simple  but  very  adequate  little  instrument. 


REQUISITES    OF    A   PULP    TESTIjSTG    OUTFIT 


37 


The  working  end,  i.e.,  the  uninsnlated  metal  part,  of 
the  electrode  (Fig.  14)  should  be  bent  at  an  angle  of  about 
45  degrees  to  the  long  axis  of  the  instrument.    Different 


TA    -UM. 


UM/ 


Fig.  10.  Fig.  11.  Fig.  12. 

Figs.    10,    11    and    12. — Wrong   types    of    dental    electrodes.      Too    much    exposed    (i.e., 
uninsulated)    metal,   and    the   wrong   shapes.      UM.,    Uninsulated    metal. 


38  ELECTEO-KADIOGRAPHIC   DIAGNOSIS 

operators  may  wish  to  vary  this  angle  slightly.  This  may 
be  done  with  a  pair  of  pliers  without  injury  to  the  in- 
strument. 

The  Indifferent  or  Hand  Electrode 

The  type  of  hand  (also  called  indifferent  or  neutral) 
electrode  illustrated  in  Fig.  15  is  familiar  to  almost  every- 
body. 

Fig.  16  shows  a  camouflaged  type  of  hand  electrode. 
The  sight  of  it  does  not  remind  the  patient  of  childhood 
experiences  with  a  ''shocking  machine,"  for  such  an  elec- 
trode is  not  ordinarily  used  with  a  Faradic  machine. 


Fig.   13. — A  combination   current   controller  and   dental   electrode.     Impractical,   in   the 

writer's  opinion. 

Instead  of  a  hand  electrode,  there  is  a  type  of  indiffer- 
ent electrode  which  clamps  on  the  cheek,  one  side  inside 
the  mouth,  the  other  outside,  which  may  be  used,  or  a 
sponge  may  be  strapped  to  the  Avrist,  or  a  sponge  on  a 
wooden  handle  may  be  used,  the  patient  having  the 
wooden  handle  in  one  hand  and  pressing  the  sponge 
against  the  other  hand,  or  the  arm. 

The  cheek  electrode  (Fig.  17)  is  not  a  good  one  to  use 
when  applying  the  electric  test  for  pulp  vitality,  espe- 
cially when  all  or  manj^  of  the  teeth  are  to  be  tested ;  it  is 
in  the  ivay. 

The  wrist  electrode  strapped  to  the  wrist  serves  the 
purpose  of  an  indifferent  electrode  nicely  except  that  the 
psychic  effect  of  strapping  the  electrode  fast  is  not  good 
with  some  patients.    An  advantage  in  strapping  an  elec- 


EEQUISITES    OF   A   PULP    TESTING    OUTFIT 


39 


trode  in  place  is  that  it  is  held  against  the  tissues  at  uni- 
form pressure.  Instead  of  strapping  it  to  the  wrist,  this 
electrode  may  be  held  in  the  hand,  like  a  hand  electrode, 
if  desired. 


urn 


Fig.  14. — The  riglit  kind  of  dental  electrode.  Simple,  efficient,  insulated  save  at 
extreme  working-  end.  Will  reach  all  parts  of  all  teeth  without  some  metal  part 
coming  in  contact  with  the  patient's  cheeks,  lips  or  tongue  or  operator's  hands. 


40 


ELECTRO-RADIOGRAPHIC    DIAGNOSIS 


The  sponge  on  a  handle  is  an  adequate  electrode  and 
serves  to  keep  the  patient  somewhat  occupied,  a  good 
thing  from  a  pyschic  standpoint.    However,  this  objec- 


Fig.    IS. — The   common   type    of   hand   electrode.      (This    electrode   is   also    called    the 
"indifferent"  and  the  "neutral"  electrode.) 


Fig.   16. — Hand  electrode   of  special   design. 


Fig.   17. — A  type  of  indifferent  electrode  which  clamps  on  the   cheek.     Impractical  for 
pulp   testing,   because   in   the   way. 


tion  might  be  raised  to  the  nse  of  a  sponge  electrode. 
Care  must  be  taken  to  keep  the  sponge  moist;  Avhen  dry 
it  ceases  to  be  a  conductor  of  electricity. 


REQUISITES    OF    A    PULP    TESTING    OUTFIT 


41 


Cotton  Holder,  Cotton  and  Blotting-  Paper  or  Napkin 

Absorbent  cotton  is  needed  to  wrap  about  tlie  point  of 
the  dental  electrode  and,  on  occasion,  to  put  nnder  the 
tongue  and  in  the  vestibule  of  the  mouth  to  keep  the  parts 
dry  while  the  test  is  applied. 

Dentists  all  have  cotton  holders.  Physician  radio- 
graphers, however,  who  do  dental  radiographic  work  and 
use  the  electric  test  to  check  their  radiographic  findings 
will  find  themselves  in  need  of  some  sort  of  holder  for 
cotton. 

Fig.  18  shows  a  cotton  holder  designed  by  the  writer. 
The  feature  of  this  holder  is  that  a  ring  of  blotting  paper 


Fig.    IS. 


Fig.    19. 


Fig.    20. 


Fig.    21. 


Fig.   IS. — Cotton   holder   with   ring   of   blotting   paper  about   base. 
Fig.  19.— Small  medicine  dish. 
Fig.  20. — Dental  mouth  mirror. 
Fig.  21. — Dental  cotton  tweezers. 

fits  over  the  dome  of  the  holder  and  rests  on  the  base. 
Those  who  do  not  wish  to  invest  in  a  manufactured  cotton 
holder  may  make  one  by  cutting  a  hole  in  the  tin  top  of 
a  glass  salve  box. 

When  the  dental  electrode  is  dipped  into  water  or  a 
salt  solution,  to  moisten  it,  it  comes  out  dripping  wet.  To 
take  up  this  excess  moisture  it  is  pressed  against  blotting- 
paper  or  a  clean  napkin. 


42  ELECTEO-EADIOGRAPHIC   DIAGNOSIS 

For  use  under  the  tongii,e  and  in  the  vestibule  of  the 
mouth,  Johnson  and  Johnson's  prepared  cotton  rolls 
will  be  desired  by  some  in  preference  to  loose  cotton  made 
into  a  roll  by  the  operator. 

Small  Medicine  Dish 

Fig.  19  shows  a  small  medicine  dish,  for  the  water  or 
saline  solution  used  to  moisten  the  cotton  on  the  dental 
electrode.  Any  sort  of  a  container  will  do  for  the  pur- 
pose, of  course.  The  writer  suggests  the  one  illustrated 
only  because  it  is  neat  in  appearance  and  cheap. 

Dental  Mouth  Mirror 

A  dental  mouth  mirror,  or  similar  instrument,  is  neces- 
sary to  assist  the  operator  in  keeping  the  tongue  and 
cheeks  out  of  the  way  while  the  electrode  is  applied  to  the 
teeth.  It  is  also  used  to  reflect  light  into  dark  parts  and 
to  "work  to  the  image," 

An  instrument  like  a  mouth  mirror,  but  made  of  some 
nonconductor,  would  be  better  than  a  metal  mouth  mir- 
ror; no  unpleasant  shock  would  occur  then  if  the  end  of 
the  dental  electrode  happened,  by  accident,  to  touch  it. 

Dental  Cotton  Tweezers 

All  dentists,  of  course,  have  such  tweezers.  Their  use 
in  connection  with  pulp  testing  is  to  carry  cotton  rolls 
under  the  tongue  and  into  the  vestibules  of  the  mouth, 
and  to  hold  cotton  to  wipe  off  the  moisture  covering  teeth. 

Record  Blanks 

It  does  little  good  to  test  teeth  with  the  electric  test 
unless  careful  records  are  kept  of  the  results.  In  my 
practice  of  radiodontia,  as  a  specialty,  it  is  my  routine 
practice  to  use  the  test  in  practically  all  cases.  With  few 
exceptions,  my  procedure  is  as  follows :  First,  the  test  is 


REQUISITES    OF   A   PULP    TESTING    OUTFIT 


43 


applied  and  records  made.  Then  the  exposures  for  the 
radiographs  are  made.  When  the  negatives  are  devel- 
oped they  are  examined  hastily  while  still  wet.  At  this 
point  some  negatives  may  be  made  over  and  some  teeth 
re-tested,  depending  on  the  particular  case  and  the  find- 
ings. The  patient  is  now  dismissed.  Then,  later,  with 
the  radiographs  mounted  and  the  electric  test  records 
and  other  records  of  the  case  before  me,  a  "report" — i.e., 
a  diagnosis,  prognosis,  etc., — is  dictated  or  written  and 


+=  Responds  to  elec- 
tric test  for  pulp  vital- 
ity. 


+  S=Re8pond9  to  elec- 
tric test  strong. 


-t  VS— Responds  to  elec- 
tric tests  very  strong. 


+  VW=  Responds  to 
electric  test  very  weak. 


-I-?— Responds  to  elec- 
tric tedlv)ut  Question  if 
this  indicates  vital  pulp. 

— ?=Doe8  not  respond 
to'electric  test  but  ques- 
tion if  this  indicates 
pulpless  tooth. 

CT=Cannot  test. 

0= Crown. 

M=Ul8Bin£. 

R=Root  or  Roots. 


Remarks; 


Treatment  and  subsequent  history:  over. 

Fig.  22. — Record  blank  used  by  the  writer  to  record  results  of  the  applications  of  the 
electric  test  for  pulp  vitality. 


sent,  with  the  negatives,  to  the  practitioner  who  referred 
the  case  for  examination. 

Fig.  22  shows  the  record  blank  used  to  record  results 
of  the  application  of  the  electric  test  for  pulp  vitality. 

While  the  vast  majority  of  teeth  may  be  marked  simply 
positive  (+)  or  negative  (-),  it  will  be  seen  from  the  rec- 
ord sheet  that,  so  far  as  this  writer  is  concerned  at  least, 
it  is  not  always  a  simple  matter  of  marking  each  tooth 
plus  or  minus.  The  results  of  the  application  of  the  test 
are  not  always  definite  enough  to  justify  this.    It  is  fre- 


44  ELECTRO-EADIOGRAPHIC    DIAGISTOSIS 

quently  necessary  to  reserve  judgment  until  both  the 
radiographic  negative  and  the  tabulated  results  of  the 
application  of  the  test  can  be  studied. 

From  the  record  sheet  it  Avill  be  seen  that  a  tooth  may 
be  marked  in  any  one  of  eight  ways:  (1)  Positive,  (2) 
Negative,  (3)  Positive  Strong,  (4)  Positive  Very  Strong, 
(5)  Positive  Weak,  (6)  Positive  Very  Weak,  (7)  Positive 
Questionable,  (8)  Negative  Questionable.  I  use  still  an- 
other marking,  i.e..  Positive  Little  Weak  (+L.  W.). 

Just  how  each  operator  will  mark  his  chart  will  per- 
haps be  a  matter  for  personal  decision,  but  I  feel  safe  in 
saying  that  no  operator  with  even  a  moderate  degree  of 
skill  in  the  use  of  the  test  will  find  the  two  marks  (nega- 
tive and  positive)  sufficient. 


CHAPTER  IV 

FUNDAMENTALS  IN  TECHNIC  OF  APPLYING 
ELECTEIC  TEST 

It  will  be  obvious  that  the  description,  given  here,  of 
the  technic  of  the  application  of  the  electric  test  is  given 
with  the  Faradic  type  of  pulp  tester  in  mind.  However, 
the  principles  of  the  technic  set  forth  are  similar  no  mat- 
ter what  type  of  machine  is  used. 

Note  the  following  in  Fig.  23:  (1)  Main  switch.  (2) 
The  interrupter.  (3)  The  current  controller,  i.e.,  the 
sliding  tube  or  sheath  (Fig.  2),  or  rheostat  Fig.  3.  (4) 
The  hand,  or  indifferent,  electrode.  (5)  The  dental,  or 
active,  electrode.  (6)  The  little  sockets  where  the  elec- 
trode cords  are  connected  to  the  machine. 

There  are  usually  three  places  or  sockets  into  which  the 
cords  may  be  plugged.  From  left  to  right  these  sockets 
may  be  designated  either  by  a  letter  or  a  number  thus: 
L.  M.  r!  or  1,  2,  3.  Fig.  2  shows  the  three  "sockets"  or 
binding  posts. 

With  the  cords  plugged  into  1  (L)  and  2  (M)  the  out- 
put current,  is  weakest.  With  the  cords  plugged  into  1 
(L)  and  3  (R)  the  output  current  is  strongest.  With  the 
cords  plugged  into  2  (M)  and  3  (R)  an  intermediate  cur- 
rent strength  is  attained. 

It  makes  practically  no  difference  about  polarity. 
Either  electrode  may  be  attached  to  any  socket. 

When  using  a  machine  Avitli  the  three  sockets,  the 
writer  uses  the  connection  1  (L)  to  3  (R)  only  for  all 
cases  to  avoid  the  necessity  of  changing  uninsulated 
plugs.  (See  Chapter  V  under  the  heading  ''A  Valuable 
Point  in  Technic") 

45 


46 


ELECTKO-EADIOGEAPHIC    DIAGNOSIS 


Speaking  of  the  control  of  the  output  current  of  the 
ordinary  commercial  Faradic  machines  with  the  three 
sockets,  one  may  say  that,  like  automobiles,  they  have 
three  speeds  or  strengths: 

First  or  low  1-2  (L-M) 

Second  or  intermediate  2-3  (M-K) 

Third  or  high  1-3  (L-E) 

Continuing  the  analogy,  the  current  controller  is  now 
the  throttle. 


INTERRUPTER 


r^. 


CURREMT 
CONTROLLER 


^l^ELECTRODE 


DENTAL 
ELECTRODE 


Fig.  23. 

From  here  on  the  steps  in  technic  will  be  numbered 
consecutively.  . 

First:  Plug  the  cords,  to  which  the  hand  and  dental 
electrodes  are  attached,  into  the  machine. 

Second :  Wrap  the  metal  point  of  the  dental  electrode 
with  cotton. 

Third :  Moisten  the  cotton  in  water  or  a  sodium  chlo- 
rid  solution. 


TECHNIC    OF    ELECTEIC    TEST  47 

Fourth :  Expel  the  extreme  excess  moisture  by  touching 
lightly  to  blotting  paper  or  napkin. 

Fifth :     Have  loatient  hold  the  hand  electrode. 

Sixth:  Turn  on  the  current  at  the  main  switch.  If 
this  does  not  cause  a  humming  noise,  fap  the  machine  or 
the  interrupter  sharply.  If  this  does  not  start  the  hum- 
ming, adjust  the  interrupter  screiv. 

Seventh:  "With  the  current  controller  set  to  give  the 
minimum  current,  touch  the  tooth  to  he  tested  ivith  the 
dental  electrode.  (When  the  sliding  tube  is  the  form  of 
current  controller,  start  with  the  tube,  or  sheath  or  cylin- 
der, all  the  way  in,  and  pull  it  out  to  increase  the  current. 
When  all  the  way  out,  the  maximum  current  is  deliv- 
ered.) 

Eighth:  Advance  the  current  controller  (i.e.,  pull  out 
the  sliding  sheath  or  advance  rheostat)  gradually,  as 
necessary  to  get  sensation,  proceeding  in  this  manner: 
Increase  the  strength  of  the  current  a  little;  touch  the 
tooth  with  the  dental  electrode.  If  there  is  no  sensation, 
increase  the  strength  of  the  current  a  little  more ;  touch 
the  tooth  with  the  dental  electrode  again  and  so  on,  until 
sensation  is  produced  or  the  capacity  of  the  machine  has 
been  reached. 

The  sensation  will  occur  in  the  tooth  only — not  in  the 
hand — provided  the  pulp  is  vital.  If  the  pulp  is  not 
vital  there  will  be  no  sensation  with  the  machine  oper- 
ating at  capacity,  i.e.,  with  the  current  controller  at  maxi- 
mum. 

It  is  not  necessary  to  start  Avitli  the  current  controller 
at  minimum  for  all  the  different  teeth  in  the  same  mouth. 
It  will  be  found  that  the  different  teeth  resjDond  at  ap- 
proximately the  same  current  strength — the  "irritation 
point"- — and  the  current  controller  may  be  left  set  ac- 
cordingly and  advanced  only  when  necessary  to  produce 
sensation.  However,  better  start  at  minimum  if  the  teeth 
give  promise  of  being  especially  susceptible.    The  lower 


48  ELECTEO-RADIOGEAPHIC    DIAGiSTOSIS 

teetli  and  teetli  Avitli  the  enamel  worn  off  exposing  the 
dentin  are  usually  quite  sensitive.  (See  Chapter  W  for 
further  discussion  of  this  subject  of  the  amount  of  current 
needed.) 

Tracing  the  Current 

The  circuit,  or  course,  or  path  of  the  current,  when  the 
Faradic  or  galvanic  electric  test  is  applied,  is  as  follows : 
from  the  machine,  through  the  dental  electrode,  into  the 
patient's  tooth,  through  the  patient,  out  of  the  patient 
through  the  hand  electrode  back  to  the  machine.  Or  the 
current  may  follow  the  same  path  but  travel  in  the  oppo- 
site direction;  the  test  can  be  made  with  the  current 
passing  in  either  direction. 

The  circuit  is  entirely  different  when  the  electrode  in 
Fig.  13  is  used.  The  current  passes  from  the  machine 
through  the  electrode  into  the  tooth,  through  the  patient, 
out  of  the  patient  into  the  operator's  left  hand  (which,  of 
course,  must  be  in  contact  with  the  iDatient)  through  the 
operator,  back  to  the  electrode  held  in  the  right  hand  and 
so  to  the  machine,  thus  completing  the  circuit. 

Perhaps  I  can  make  the  foregoing  clearer  if  I  say  that 
when  an  electrode  like  that  shown  in  Fig.  13  is  used,  the 
operator's  left  hand  becomes. the  indifferent  electrode,  the 
operator's  body  the  conducting  cord,  and  the  right  hand 
forms  the  attachment  or  plug  into  the  machine. 

Not  having  to  use  an  indifferent  electrode  is,  in  itself, 
an  advantage  but  this  type  of  electrode  has  other  and 
serious  disadvantages. 

"\^Tien  a  high-frequency  machine  is  used,  no  circuit  is 
needed.  The  current  is  so  high  in  voltage,  i.e.,  pressure, 
it  jumps  into  the  tooth,  as  a  spark,  when  the  electrode  is 
even  brought  close  to  the  tooth  before  it  touches.  This 
occurs  Avithout  any  other  electrical  connection  between 
the  patient  and  the  machine,  and  without  the  patient 


TECHNIC    OF    ELECTRIC    TEST  49 

touching  a  ground  to  induce  tlie  current  to  enter  and  pass 
through  the  body.  A  ground  may  be  defined  as  any  elec- 
trical path,  like  a  gas  or  water  pipe,  for  example,  or  a  wet 
floor  which  theoretically,  at  least,  leads  eventually  to  the 
earth. 


CHAPTER  V 
SPECIAL  POINTS  IN  TECHNIC 

A  Valuable  Point  in  Technic 

As  stated  in  Chapter  IV,  when  the  machine  nsed  has 
three  sockets  (Figs.  2  and  4),  the  electrode  cords  are 
plugged  into  ''L-R,"  i.e.,  1  and  3.  It  is  awkward  and  im- 
practical to  keep  changing  comiections  (by  means  of  un- 
insulated plugs  especially)  when  a  number  of  teeth  are 
to  be  tested.  However,  with  the  cords  plugged  into  L-R 
and  the  current  controller  at  minimum — particularly 
when  the  cell  in  the  tester  is  new — the  machine  may  be 
found  to  deliver  a  current  slightly  stronger  than  desirable 
for  some  cases*  In  this  event,  do  not  actually  touch  the 
teeth  with  the  dental  electrode.  Make  the  cotton  on  the 
dental  electrode  quite  moist,  and  place  it  close  to  the 
tooth  being  tested  until  the  water  from  the  moist  elec- 
trode is  seen  to  touch  the  tooth  and  so  establish  an  elec- 
tric connection  (Fig.  24).  The  amount  of  current  i^assing 
into  the  tooth  will  vary  somewhat  according  to  the  per- 
fection of  the  electric  connection  or  contact  of  the  dental 
electrode  with  the  tooth,  and  the  water  connection  is  ob- 
viously not  as  perfect  as  though  the  cotton  were  placed  in 
actual  contact  with  the  enamel. 

This  procedure  of  making  the  "moisture  contact"  will 
also  help  the  operator  very  much  in  cases  of  extremely 
nervous  patients  who  always  flinch  in  anticipation  of  pain 
whenever  they  feel  the  electrode  touch  the  tooth,  for  the 
electrode  does  not  touch  the  tooth  and  the  patient  does 
not  know  when  the  connection  is  made,  unless  he  is  receiv- 
ing electrical  sensation. 


*It  must  be  conceded  here  that  some  Faradic  machines  give  such  a  strong  current 
with  the  plugs  in  L-R,  and  tJie  sliding  sheath  clear  in,  that  they  are  not  amenable  to 
the  expedient  here  suggested.     Such  machines  do  not  make  good  pulp  testers. 

50 


SPECIAL    POINTS    IN    TECHNIC 


51 


Steady  the  Hand 

To  make  the  imperfect,  moisture  contact,  one  must 
steady  the  hand  by  supiDorting  it  with  the  fingers  against 
the  patient's  face  or  teeth.  However,  the  hand  manipu- 
lating the  dental  electrode  should  always  be  steadied  in 
this  fashion  whether  one  is  making  the  moisture  contact 
or  ordinarv  contact. 


Fig.   24. — Moisture   contact,   not  actual   contact. 

Keep  Teeth  Moderately  Dry 

The  teeth  being  tested  should  be  kept  moderately  dry ; 
with  cotton  rolls  Avhen  neeessarj^.    Otherwise  the  current 


52  ELECTEO-EADIOGRAPHIC    DIAGNOSIS 

may  pass  into  the  gum,  pericemental  membrane  and  ap- 
proximating teeth,  through  the  saliva.  The  writer  finds 
from  experience  it  is  not  necessary  to  keep  the  teeth  as 
dry  as  he  at  first  supposed  necessary.  Cotton  rolls  are 
rarely  necessary  for  upper  teeth. 

For  the  lower  teeth,  instruct  the  patient  to  "raise  the 
tip  of  the  tongue  to  the  roof  of  the  mouth,"  then  place 
the  cotton  roll  and  instruct  the  patient  to  ''forget  about 
the  tongue."  The  cotton  thus  applied  is  as  useful  as  a 
means  of  keeping  the  tongue  away  from  the  teeth  as  to 
keep  them  dry.  Use  plenty  of  cotton,  tightly  rolled,  un- 
der the  tongue.  Only  about  one  fourth  as  much  cotton 
can  be  placed  on  the  buccal  (facial)  side  of  the  teeth  as 
can  be  placed  on  the  lingual  side. 

Unruly  Tongues 

In  cases  where  the  tongue  is  very  unruly,  pushes  the 
cotton  out  of  the  mouth,  insists  on  covering  the  teeth 
when  the  operator  wishes  to  apply  the  electrode,  if  the 
operator  will  allow  the  electrode  to  touch  the  unruly  mem- 
ber, accidentally  (?),  once  or  twice  the  patient  not  infre- 
quently acquires  a  sudden  and  very  fortunate  control 
over  the  unruly  lingual  member. 

Wrapping  the  Dental  Electrode 

It  is  apparently  a  very  simple  thing  to  Avrap  the  point 
of  the  dental  electrode  with  cotton,  just  as  the  whole 
technic  of  electric  pulp  testing  is  simple,  yet  how  easy  it 
is  to  do  it  wrong,  and  therefore  how  often  it  is  done 
wrong.  A  sufficient  amount  of  cotton  to  cover  the  metal 
well  and  leave  a  little  pad  on  the  end  should  be  wrapped 
tightly  about  the  exposed  metal.  Rest  the  cotton  be- 
tween the  fingers  and  thumb  of  the  left  hand  and  turn  the 
instrument  to  wrap. 

If  the  cotton  does  not  wrap  about  the  metal  readily, 
flatten  the  sides  with  a  stone  or  file.    This  is  better  than 


SPECIAL   POIXTS    IN    TECHNIC 


53 


nicking  the  metal  witli  a  file;  the  cotton  goes  on  the  flat- 
tened electrode  just  as  readily  and  comes  off  easier.  (See 
Figs.  25  and  26.) 

Twisting  the  cord,  and  the  consequent  danger  of  break- 
ing it  may  be  avoided  by  disconnecting  the  electrode  from 
the  cord  while  the  cotton  is  wrapped  on  the  former. 


l-ig.  25. 


Fig.  26. 


Fig.  25. — Showing  how  the  cotton  should  be  wrapped  on  the  dental  electrode. 

Fig.    26. — Wrong  way   to   wrap   the    dental   electrode   with   cotton;    too   much 

cotton  too   loosely  wrapped. 


54  ELECTEO-EADIOGRAPHIC    DIAGNOSIS 

The  Application  of  the  Dental  Electrode  to  the  Various 

Teeth 

It  does  not  make  a  great  deal  of  difference  which  par- 
ticular part  of  a  normal  tooth  is  selected  as  the  spot  on 
which  to  apply  the  dental  electrode.  However,  the  writer 
finds  himself  following  the  selection  indicated  by  the 
table  Selection  of  Spot  for  the  Application  of  the  Den- 
tal Electrode  when  fillings  do  not  interfere  with  such 
selection. 

Selection  of  Spot  for  the  Application  of  the  Dental  Electrode 


Anterior  Teeth 


First  choice:     the  labial  surface 
V  Second  choice:     the  incisal  edge 
Upper  and  Lower    [  Tj^^^d  choice :     the  lingual  surface 


Upper  Bicuspids 
And  Molars 


First    choice:      the   lingual   surface    (near    summit    of 

lingual  cusps,  at  first) 
Second  choice :     the  buccal  surface 
Third  choice:     the  fossse 


Lower  Bicuspids     j  First  choice :     Buccal  or  ling-ual  surface  near  occlusal 
And  Molars  |  Second  choice :     the  fossae 

Using  Side  of  Dental  Electrode 

If  touching  the  tooth  with  the  end  of  the  electrode 
(Fig.  27)  does  not  produce  sensation,  lay  the  side  of  the 
electrode  against  the  surface  of  the  tooth  (Fig.  28).  By 
gaining  a  greater  area  of  contact  more  electricity  enters 
the  tooth. 

Keep  Away  from  Gum  Tissue 

When  applying  the  side  of  the  electrode  to  facial  or 
lingual  surfaces  of  teeth,  take  care  not  to  allow  the  end 
of  the  electrode  to  approach  too  near  the  gum  line  as  the 
current  may  pass  through  moisture  into  the  gum  tissue. 
Take  care  not  to  mistake  sensation  caused  in  this  manner 
for  sensation  due  to  a  vital  pulp;  there  is  a  difference  in 
the  character  of  the  sensation. 


SPECIAL   POINTS   IN    TECHNIC 


55 


When  to  Apply  the  Electrode  to  the  Lingual  Surface  of 
Anterior  Teeth 

When  sensation  cannot  be  gained  by  applying  the  elec- 
trode to  the  facial  surface  or  incisal  edge  of  an  anterior 
tooth,  apply  it  to  the  lingual  surface,  where  the  covering 
of  tooth  structure  over  the  pulp  is  not  so  thick.  (Fig.  14 
is  of  the  correct  shape  to  reach  the  lingual  surfaces  con- 
veniently.) 


Fig.  27. 


Figs.  27  and  28. — If  a  contact  like  that  illustrated  in  Fig.  27  does  not  give 
sensation,  try  a  contact  like  that  shown  in  Fig.  28.  The  greater  area  of  contact  in 
Fig.  28  makes  it  possible  for  more  current  to  enter  the  tooth.  In  Fig.  27  only  the 
point  of  the   electrode  touches  the  tooth;   in   Fig.  28  the  side  of  the  electrode  touches. 

When  and  How  to  Apply  the  Electrode  to  Fossae 

When  sensation  cannot  be  gained  by  aiDplying  the  elec- 
trode to  the  cusps  or  facial  or  lingual  surfaces  of  the  pos- 
terior teeth,  apply  the  electrode  to  a  cusp,  then  slide  it 
down  into  the  fossa  slowly.  The  presence  of  a  large  fill- 
ing may  make  this  procedure  imiDracticable. 


56 


ELECTRO-RADIOGRAPHIC    DIAGNOSIS 


How  Much  Sensation  (Pain?)  to  Cause 

It  is  best  to  use  enough  current  to  cause  the  patient  to 
jump  or  flinch  involuntarily;  slightly,  but  definitely. 

My  interest  was  thoroughly  aroused  when  I  read  the 
following  in  an  advertisement  for  a  pulp  tester:  ''En- 
ables you  to  detect  devitalized  teeth  with  certainty  and 


Fig.  28. 

speed  and  ivithout  causing  pain."  Considering  my  ex- 
perience with  other  pulp  testing  machines  this  adver- 
tisement led  me  to  believe  that  the  manufacturers  meant 
to  say  to  me  that  they  had  a  machine  different  from  the 
pulp  testing  machines  I  had  used  in  that  it  did  not  cause 
pain  like  other  electric  pulp  testers.  Investigation, 
however,  proved  that  the  pulp  testing  machine  adver- 
tised was  not  different  from  others.    It  caused  the  same 


SPECIAL   POINTS    IN"    TECHNIC  57 

sort  of  sensation  caused  by  all  electric  pulp  testers. 
Whether  it  caused  only  a  '^distinct  sensation"  as 
claimed,  or  a  slight  pain  is  merely  a  matter  of  diction, 
merely  a  matter  of  Avhat  you  choose  to  call  the  sensation. 
Can  any  one  tell  just  where  "distinct  sensation"  leaves 
off  and  slight  pain  begins?  The  manufacturer  evidently 
believes  we  should  say  "distinct  sensation"  rather  than 
"slight  pain"  and  I  am  inclined  to  agree  with  him,  but 
patients,  I  fear,  will  continue  to  call  it  pain.  Person-  \ 
ally  I  should  describe  the  sensation  as  a  warm,  stinging' 
sensation,  very  slightly  painful  or  very  definitely  pain- 
ful, depending  on  the  strength  of  the  current. 

Do  not  Touch  Tongue,  Lips,  Cheeks  or  Gums  with  Dental 

Electrode 

Take  care  not  to  touch  the  patient  with  the  dental  elec- 
trode anj^where  but  on  the  tooth  to  be  tested  as  the  sen- 
sation would  be  unpleasant.  Hence  the  necessity  of  a 
dental  electrode  perfectly  insulated  except  at  its  end.  The 
fingers  and  a  mouth  mirror  are  used  to  hold  back  tongue, 
lijDS,  and  cheeks. 

Crowned  Teeth 

Crowned  teeth  cannot  be  tested.  Sensation  is  always 
produced  whether  the  pulj^  is  vital  or  not,  if  the  crown  is 
a  gold  shell.  If  the  crown  is  one  of  the  post-in-the-canal 
variety,  testing  is  unnecessary  for  we  know  the  ]3ulp  is 
not  vital.  I  have  attempted  to  test  only  a  comparatively 
few  teeth  with  porcelain  jacket  crowns,  and  have  found 
it  impossible  to  get  a  reaction:  the  porcelain  acts  as  a  \ 
non-conductor. 

Testing  Teeth  with  Large  Metal  Fillings 

Teeth  with  large  metal  fillings  cannot  be  tested  at  all 
if  the  filling  is  so  large  there  is  no  spot  of  sound  enamel 
to  which  the  dental  electrode  may  be  touched.  However, 
when  there  is  a  spot  of  sound  enamel  to  which  the  dental 


58  ELECTKO-RADIOGEAPHIC   DIAGNOSIS 

electrode  may  be  applied  teeth  with  large  fillings  can  be 
tested  much  more  successfnlly  I  find  from  experience  than 
one  would  imagine. 

Metal  Fillings  Which  Should  Not  be  Touched  with 
Dental  Electrode 

When  testing  a  tooth  with  an  approximo-occlusal  or  an 
approximo-incisal  filling,  or  any  filling  passing  beneath 
the  gum  margin  or  touching  an  approximating  tooth,  do 
not  touch  the  filling — touch  the  enamel  only.  Also  avoid 
touching  unsupported  enamel  with  a  metal  filling  just 
under  it,  as  the  effect  is  about  the  same  as  touching  the 
metal,  i.e.,  there  will  be  a  sharp  positive  reaction  whether 
the  pulp  is  vital  or  not. 

Rubber  Dam  Insulation 

When  testing  teeth  with  approximo-occlusal  or  ap- 
proximo-incisal fillings  in  them,  two  or  more  thicknesses 
of  rubber  dam  may  sometimes  be  placed  between  the  fill- 
ing and  the  tooth  approximating  the  filling.  If  kept  dry, 
the  rubber  acts  as  an  insulation,  keeping  the  current  from 
passing  into  the  approximating  tooth.  I  find,  however, 
as  I  develop  a  better  technic  and  judgment  I  am  able  to 
discontinue  the  use  of  this  rubber  dam  insulation. 

When  and  How  to  Touch  a  Metal  Filling  with  the 
Dental  Electrode 

A  tooth  with  a  small,  simple  filling  surrounded  by 
sound  enamel,  which  does  not  come  in  contact  with  the 
gum  tissue  or  approximating  tooth,  may  be  tested  by 
touching  the  dental  electrode  to  the  filling.  When  this  is 
done,  the  current  should  he  weak;  also  it  is  best  to  apply 
the  electrode  to  the  enamel  and  slide  it  cautiously  toward 
the  filling. 


SPECIAL   POINTS    IN    TECHNIC  59 

If  tlie  filling  is  large,  even  tliongli  it  does  not  come  in 
contact  with  the  gum  tissue  or  approximating  tooth,  it  is 
not  expedient  to  touch  it  with  the  dental  electrode.  If 
the  pulp  is  vital,  the  pain  produced  may  be  very  intense, 
if  it  is  not  vital,  sensation  is  sometimes  nevertheless 
caused  owing  to  the  attraction  the  big  bulk  of  metal 
filling  material  has  for  the  current,  receiving  it  in  such 
quantities  it  is  transmitted  to  the  pericemental  membrane 
and  contiguous  tissues  or  in  some  cases  perhaps  trans- 
mitted by  moisture  through  unfilled  canals  to  the  periapi- 
cal tissues. 

Unsupported  Enamel 

Avoid  touching  unsupported  enamel.  If  it  overlies  a 
filling  substantially  the  same  effect  is  produced  as  though 
the  electrode  were  applied  directly  to  the  filling,  and  if  it 
covers  a  carious  cavity  the  current  passes  through  it  into 
the  cavity  and  so  through  moisture  into  the  pulp,  produc- 
ing a  violent  reaction  if  the  pulp  is  vital.  Even  if  the 
pulp  is  not  vital  a  reaction  usually  occurs  from  touching 
unsupported  enamel  over  an  approximo-occlusal  carious 
cavity;  the  current  passes  into  the  moisture  in  the  cavity 
and  thus  into  gum  tissue,  pericemental  membrane  and  ap- 
proximating tooth. 

Trouble:  No  Current 

The  first  time  it  occurred  it  puzzled  me:  the  machine 
(one  of  the  Faradic  type)  was  humming  as  it  should,  the 
patient  held  the  hand  electrode,  the  dental  electrode  was 
moist.  I  applied  the  dental  electrode  and  advanced  the 
current  controller  from  the  minimum  to  maximum;  no 
reaction.  I  tried  another  tooth  and  another  and  another; 
still  no  reaction. 

I  took  the  hand  electrode  in  my  own  hand  and  with 
the  current  controller  at  minimum  applied  the  dental 


60 


ELECTRO-RADIOGRAPHIC    DIAGNOSIS 


electrode  to  the  fleshy  base  of  my  thumb;  no  sensation. 
I  advanced  the  current  controller;  no  reaction. 

I  fingered  about  all  the  connections  where  the  cords 
fasten  to  the  machine  and  electrodes.  Then,  with  the 
current  controller  again  at  minimum,  tried  the  test  on 
myself  again;    Ah,  sensation! 

"Evidently  one  of  the  connections  is  loose,"  thought  I, 
and  proceeded  to  test  the  patient's  teeth.  One  tooth  was 
tested,  then  another,  then  again  I  had  no  current. 


Fig.  29. — Showing  where  cords  wear  out  and  break  A  and  one  reason  B  why 
they  break  here.  Some  tips  or  plugs  are  made  so  that  they  may  be  unscrewed  and 
the  cord  repaired  by  cutting  and  re-attaching  at  the  tip.  Cords  break  as  they  enter 
the  tips  at  their  electrode  ends  also. 

Then  it  occurred  to  me  that  perhaps  the  wire  inside 
of  the  insulation  was  broken  at  A,  Fig.  29  as  a  result  of 
plugging  the  cords  into  the  machine  as  indicated  in  Fig. 
29,  B.  Such  proved  to  be  the  case;  I  could  establish  a 
connection  between  the  broken  ends  of  the  wire  inside  the 
insulation  by  pushing  the  cords  into  the  metal  tips 
slightly,  and  break  it  again  by  pulling  on  the  cords  just 
a  little. 

Let  me  say  emphatically  that  such  a  cord  with  a  broken 
wire  should  not  be  used.    Even  though  punching  the  cord 


SPECIAL    POINTS    IN    TECHiSTIC  61 

toward  the  metal  tip  may  bring  tlie  broken  ends  of  the 
wire  in  contact,  a  slight  movement  of  the  cord  may  sepa- 
rate them  again  and  another  slight  movement  bring  them 
together  again.  So  Avitli  this  sort  of  thing  going  on  ob- 
viously one  can  scarcely  tell  Avhen  a  tooth  fails  to  respond, 
whether  it  is  because  the  pulp  is  not  vital  or  because  the 
ends  of  the  broken  Avire  have  been  separated  momenta- 
rily. 

Testing  Out  the  Machine 

Whenever  there  is  an}^  doubt  at  all  as  to  whether  the 
machine  is  producing  current,  let  the  operator  take  the 
hand  electrode  in  his  left  hand  and  touch  the  dental  elec- 
trode to  the  fleshy  part  of  his  thumb  of  the  same  hand  as 
suggested  above.  Have  the  current  regulator  at  mini- 
mum to  start  with  at  least. 

Tracing"  the  Current  When  Shock  Occurs  Changing  Plugs 

For  a  shock  to  occur  when  changing  plugs  the  condi- 
tions must  be  as  follows:  (1)  The  main  switch  must  be 
closed,  and  the  interrupter  vibrating.  (2)  The  patient 
must  be  in  contact  Avith  the  indifferent  electrode.  (3) 
The  plug,  Avliere  the  operator  grasps  it,  must  be  an  elec- 
tric conductor,  i.e.,  metal.  (4)  The  ojDerator  must  take 
hold  of  the  plug  which  is  connected  (by  the  cord)  to  the 
dental  electrode.  (5)  The  operator  must  be  in  contact 
with  the  patient. 

Shocks  occurring  when  j)lugs  are  changed  may  be 
avoided  in  a  number  of  Avays,  as  many  Avays  as  there  are 
requisites  for  the  shock  to  occur.  (1)  By  opening  the 
main  SAvitch.  This  is  rather  impractical.  (2)  By  liaAang 
the  patient  lay  doAAm  the  hand  electrode.  This  too  is  im- 
practical. (3)  By  liaA^ng  insulated  plugs.  This  is  practi- 
cal. (4)  B}^  changing  the  plug  connected  Avitli  the  in- 
different electrode.     This  is  sometimes  practical,  some- 


62  ELECTRO-EADIOGEAPHIC    DIAGNOSIS 

times  not.  (5)  By  the  operator  severing  all  electrical  con- 
nection with  patient  before  touching  plugs.  This  will 
"work,"  but  is  a  nuisance.  In  fact  the  whole  procedure 
of  changing  plugs  is  a  nuisance,  as  stated  under  the  head- 
ing "A  Valuable  Point  in  Technic." 

The  course  of  the  current  when  shock  due  to  plug 
changing  occurs  is  as  follows:  From  the  machine  to  the 
patient,  through  the  indifferent  electrode.  From  the  pa- 
tient, through  the  operator's  hand  or  metal  mouth  mirror 
(in  contact  with  the  patient),  through  the  operator's 
hand  which  grasps  the  plug,  and  thus  back  to  the  ma- 
chine, or  following  the  same  path  in  the  opposite  direc- 
tion. 

TECHNIC  ILLUSTRATED    (Figs.  30  to  41) 

Even  my  technic  is  not  always  exactly  as  shown  in  the 
following  illustrations.  The  illustrations  are  shown  not 
with  the  idea  that  the  reader  shall  always  do  just  as  il- 
lustrated. However,  no  written  description  of  how  to  do 
a  thing  can  be  as  efficacious  as  to  show  how  to  do  it. 
Therefore  these  illustrations,  I  feel  certain,  will  be  quite 
helpful. 

There  are  no  illustrations  in  this  series  showing  the  ap- 
plication of  the  dental  electrode  to  the  incisal  edges  and 
occlusal  surfaces.  By  illustrating  the  application  of  the 
electrode  to  the  facial  and  lingual  surfaces  all  essential 
points  in  technic  are  demonstrated. 

It  seems  obvious  to  the  writer  but  it  may  be  mentioned, 
however,  that  it  is  the  point  of  the  electrode  usually 
which  is  used  when  it  is  applied  to  incisal  edges  and  oc- 
clusal surfaces. 

Read  the  legends  under  the  illustrations  from  Fig.  30 
to  Fig.  41  inclusive. 

Figs.  30  to  41  show  the  positions  of  the  hands,  mouth 
mirror  and  electrode  when  the  latter  is  applied  to  the 
different  teeth.  It  is  my  habit  to  hold  the  mouth  mirror 
in  the  left  hand  even  when  it  is  not  in  use. 


SPECIAL   POINTS    IN    TECHNIC 


63 


The  position  of  the  operator  is  to  the  right  and  just 
back  of  the  patient,  i.e.,  the  usual  dental  operating  posi- 
tion. Most  all  of  the  teeth  can  be  reached  from  this 
position.  It  may  be  found  advantageous  to  step  forward 
from  the  usual  position  and  face  the  patient  to  reach  the 
right  posterior  teeth,  particularly  the  buccal  surfaces  of 
the  upper  second  and  third  molars. 

Notice  that  the  hand  that  holds  the  electrode  is  always 
supported — "guarded"  to  use  the  word  usually  used  in 
this  connection—  against  the  teeth  or  face,  so  the  elec- 
trode may  be  applied  exactly  to  the  right  spot  of  the  right 
tooth. 

In  several  of  the  illustrations,  from  Fig.  30  to  Fig.  41, 
the  cotton  on  the  electrode  has  been  discolored  with  iodin 
to  make  it  show  plainer  against  the  white  of  the  teeth. 


Fig.  30. — Applying  the  electrode  to  the  labial  surface  of  an  upper  anterior  tooth. 
The  cotton  on  the  electrode  point  is  stained  with  iodine  to  make  it  show  plainer 
in   the  illustration. 


64 


ELECTRO-EADIOGRAPHIC    DIAGNOSIS 


Fig.  31. — Applying  the  electrode  to  the  lingual  surface  of  an  upper  anterior  tooth. 
The  operator  "works  to  image,"  i.e.,  he  sees  the  end  of  the  electrode  and  the  lingual 
surfaces  of  the  teeth  in  the  mouth  mirror. 


SPECIAL    POINTS    IN    TECHNIC 


65 


Fig.  32. — Applying  the  electrode  to  the  buccal  surface  of  an  upper  left  posterior 
tooth.  Note  how  the  mouth  mirror  is  used  to  hold  away  the  cheek  and  how  the 
hand  holding  the  electrode  is  steadied  by  placing  the  fingers  against  the  upper  anterior 
teeth — also  resting  slightly  against  chin. 


66 


ELECTRO-EADIOGRAPHIC    DIAGNOSIS 


Fig.  33. — Applying  the  electrode  to  the  lingual  surface  of  an  upper  left  posterior  tooth. 


SPECIAL    POINTS   IN    TECHNIC 


67 


Fig.  34. — Applying  the  electrode  to  the  buccal  surface  of  an  upper  right  posterior 
tooth.  Position  of  operator  is  farther  forward  than  usual  for  other  teeth.  Note 
electrode   hand   is   supported   against   lower   teeth   and   chin. 


ELECTRO-EADIOGEAPHIC    DIAGNOSIS 


Fig.    35. — Applying    the    electrode    to    the    lingual    surface    of    an    upper    right   posterior 
tooth.     Working  to  the  image  in  the  mirror. 


SPECIAL   POINTS    IN    TECHNIC 


69 


Fig.    36. — Applying   the   electrode   to   the   labial   surface   of   a   lower   anterior   tooth. 


70 


ELECTRO-RADIOGRAPHIC    DIAGNOSIS 


Fig.   Z7 . — Applying  the  electrode  to  the  lingual   surface  of  a  lower  anterior  tooth. 


SPECIAL  POINTS   IN"   TECHNIC 


71 


^^^0^^^         -'^^^ 

^H 

I^F   _.v*:#^            .,^ 

>      * 

M           ^  f 

<  / 

j^ 

V 

Fig.  38. — Applying  the  electrode  to  the  buccal  surface  of  a  lower  left  posterior 
tooth.  Note  the  cotton  roll  under  the  tongue.  There  is  also  a  small  roll  of  cotton 
in  the  vestibule  of  the  mouth.     The  mouth  mirror  is   used  to   retract  the   cheek. 


72 


ELECTRO-RADIOGRAPHIC    DIAGNOSIS 


Fig.  39. — Applying  the  electrode  to  the  lingual  surface  of  a  lower  left  posterior 
tooth.  Cotton  under  the  tongue  and  in  the  vestibule  of  the  mouth.  Here  the  mouth 
mirror  is  used  to  reflect  light  onto  the  field  of  operation;  the  middle  finger  of  the 
left  hand  retracts  the  cheek. 


SPECIAL   POINTS    IN    TECHNIC 


73 


Fig.  40. — Applying  the  electrode  to  the  buccal  surface  of  a  lower  right  posterior  tooth. 
The  mirror   is  holding  the   cotton   and   tongue   down. 


74 


ELECTRO-EADIOGRAPHIC    DIAGISTOSIS 


Fig.  41. — Applying  the  electrode  to  the  lingual  surface  of  a  lower  right  posterior 
tooth.  The  cheek  and  face  serve  as  a  support  for  the  hand  holding  the  electrode. 
The  mirror  retracts  the  tongue.  Cotton  under  tongue  and  in  vestibule  of  mouth. 
Electrode  hand  retracts  cheek. 


CHAPTER  VI 

THINGS  WHICH  MODIFY  THE  STEENGTH  OF 
CURRENT  NECESSARY  TO  TEST  TEETH 

In  tlie  same  month  some  teeth  will  reqnire  more  cnrrent 
than  others.  This  varies  somewhat  in  proportion  to  the 
size  of  the  tooth.  However,  it  is  quite  impossible  to  es- 
tablish the  ''irritation  point"  (the  point  where  definite 
sensation  is  prodneed)  of  the  various  teeth  with  mathe- 
matical precision.  To  sa^^,  for  example,  that  the  ' '  irrita- 
tion point"  for  lower  incisors  is  one  (scale  1  to  10,  mini- 
mum to  maximum,  of  the  current  controller),  of  upper 
incisors,  two,  of  upper  cusjDids,  six,  of  upper  molars  five 
and  so  on.  There  are  too  many  factors  which  modify  the 
streno'th  of  the  current  needed  to  admit  of  making  such 
a  table. 

A  List  of  Factors  Modif5dng  Stren^h  of  Current  Needed 

Some  of  these  factors  are:  (1)  Age  of  the  patient.  (2) 
Thickness  of  the  enamel.  (3)  Condition  of  the  patient. 
(4)  Moisture.  (5)  Secondary  dentin.  (6)  Pulp  stones. 
(7)  Abrasion  and  erosion.  (8)  Carious  cavity.  (9)  Im- 
munity to  current.  (10)  Fillings.  (11)  Size  of  tooth. 
(12)  Pericementitis. 

Age  of  Patient 

The  younger  the  jDatient,  the  larger  the  pulp,  and  so 
the  shorter  the  distance  to  it  through  the  tooth.  Hence 
less  current  is  required. 

Thickness  of  the  Enamel 

The  thickness  of  the  enamel  varies  in  different  indi- 
viduals, in  various  teeth,  in  different  locations  on  the  same 

75 


76  ELECTEO-EADIOGEAPHIC    DIAGNOSIS 

tootli.  The  thicker  the  enamel,  the  more  current  re- 
ciuired.  This  is  particularly  noticeable  in  the  upper  cus- 
j)icl  Adhere  the  enamel  is  quite  thick.  Most  teeth  in  the 
mouths  of  adults  are  worn  through  the  enamel  at  some 
place  or  places. 

Condition  of  the  Patient 

Not  infrequently  the  test  is  applied  in  cases  where  the 
patient  has  been  taking  some  narcotic  to  relieve  pain. 
More  current  is  required  in  such  cases  and  the  Avriter  re- 
calls having  a  case  where  large  doses  of  codein  had  been 
taken  and  no  response  at  all  could  be  obtained  from  the 
application  of  the  electric  test  at  the  cai)acity  of  the  ma- 
chine. This  case  and  one  other — a  case  in  which  there 
was  a  luetic  central  nerve  lesion — are  the  only  cases  thus 
far  encountered  where  the  "irritation  j^oint"  could  not 
be  reached. 

It  is  well  known  that  alcohol  has  a  narcotic  effect  and 
so  a  patient  under  its  influence  requires  more  current. 

Neurotic  patients  will  recpiire  less  current  than  patients 
of  a  more  phlegmatic  temperament. 

Moisture 

Teeth  which  are  thoroughly  dry  will  require  more  cur- 
rent than  those  which  are  somewhat  moist.  Thus  the 
lower  teeth  take  somewhat  less  current  than  the  upper. 
Also  the  amount  of  current  necessary  will  vary  with  the 
moisture  of  the  cotton  on  the  dental  electrode;  the  drier 
the  cotton  becomes,  the  more  current  necessary  to  pro- 
duce a  given  effect. 

Secondary  Dentin 

As  a  pulp  recedes,  throwing  up  secondary  dentin,  the 
current  required  to  reach  and  have  an  effect  on  it  nat- 
urally increases. 


STRENGTH    or    CURRENT 


77 


I  have  noticed  repeatedly  that,  though  the  upper  lateral 
incisors  are  smaller  than  the  centrals,  the  laterals  require 
more  current  to  reach  their  irritation  point.  Perhaps  the 
upper  laterals,  from  some  cause  of  which  I  am  in  ignor- 
ance, are  more  likely  to  develop  secondary  dentin,  (this 
seems  probable)  or,  it  may  be  the  enamel  on  them  is  com- 
paratively thicker  than  on  the  centrals,  or,  it  may  be  be- 
cause their  nerve  supply  is  less  generous  and  less  direct 
than  the  centrals.  At  any  rate  it  may  be  accepted  as  a 
clinical  fact,  and  an  exception  to  the  rule  that  the  amount 


Fig.  42. — In  some  cases  it  may  be  expedient  to  make  an  opening  through  the 
enamel  to  apply  the  dental  electrode.  The  advantage  in  this  over  simply  drilling  to 
the  point  of  sensitivity  is  that  there  is   less  danger  of  accidental   exposure. 


of  current  varies  directly  with  the  size  of  the  tooth,  that 
upper  laterals  usuall}^  require  a  sliglitlij  stronger  cur- 
rent than  upper  centrals. 

In  some  cases  of  secondary  dentin  where  the  pulp  is 
vital  it  is  impossible  to  get  any  response  at  all  from  the 
application  of  the  electric  test.  In  such  cases  a  small 
diagnostic  opening  may  be  made  Avitli  the  dental  burr 
through  the  enamel,  one  or  two  millimeters  into  the  den- 
tin (Fig.  42)  and  the  dental  electrode  applied  to  the 
dentin  in  this  way.    If  the  pulp  is  vital  a  response  to  the 


78  ELECTRO-RADIOGEAPHIC    DIAGISTOSIS 

electric  test  can  be  obtained  in  this  way.  In  order  to 
carry  ont  tliis  suggestion,  the  dental  electrode  must  have 
a  point  or  working  end  of  the  right  size  and  shape  (Fig. 
14). 

Pulp  Stones 

Occasionally  teeth  with  pulp  stones  require  more  cur- 
rent, unless  there  is  pulpitis,  when  less  current  is  re- 
quired. It  is  sometimes  expedient  to  make  a  diagnostic 
opening  into  the  dentin,  tlieii  apply  the  test,  as  just  sug- 
gested under  the  heading  "Secondary  Dentin." 

Abrasion  and  Erosion 

As  a  rule  less  current  is  required  on  abraded  and 
eroded  surfaces  because  there  is  less  or  no  enamel  to 
penetrate.  If  the  abrasion  or  erosion  has  caused  the  pulp 
to  recede  and  throw  up  secondary  dentin,  the  presence  of 
the  secondary  dentin  may  compensate  for  or,  in  rare  in- 
stances, more  than  compensate  for  the  loss  of  enamel. 

Carious  Cavity 

A  tooth  with  a  carious  cavity  in  it  should  be  tested  care- 
fully, applying  the  electrode  to  a  point  on  the  surface  of 
the  tooth  as  remote  as  possible  from  the  cavity.  Even 
when  this  is  done,  taking  them  as  a  class  of  teeth,  teeth 
with  carious  cavities  in  them  require  less  current  than 
teeth  without  cavities.  (The  current  seeks  the  cavity 
through  moisture.) 

Immunity  to  Current 

Practically  all  patients  will  claim  to  be  particularly 
susceptible  to  electric  shocks.  While  I  am  perfectly  well 
aware  of  the  fact  that  some  patients  can  "stand"  more 
electricity  than  others  and  try  never  to  lose  sight  of  this 
fact,  and  am  now  in  fact  directing  my  reader's  attention 


STKEXGTH    OF    CUEEEXT  79 

to  it,  I  nevertheless  know  tliat  each  patient  who  claims 
especial  susceptibility  is  not  the  exception  he  thinks  he 
is.  True  exceptions  of  subnormal  susceptibility  are  more 
common,  I  find,  after  making  allowances  for  fright,  than 
cases  of  supernormal  susceptibility.  Electricians,  men 
who  work  with  electric  currents  constantly,  are  often  sub- 
normally  susceptible,  requiring  excessive  doses  of  the  cur- 
rent to  get  a  reaction. 

It  is  common  knowledge  that  apx)lication  of  an  electric 
current  will  result  in  an  acquired  tolerance.  We  notice 
this  in  the  application  of  the  electric  test  for  pulp  vitality. 
I  have  had  this  experience  repeatedly:  I  start  to  test  a 
given  tooth  with  the  current  controller  at  minimum  to 
avoid  undue  pain.  The  controller  is  gradually  advanced, 
touching  the  tooth  at  each  advance  of  two  or  three  points 
on  the  scale,  until  the  controller  stands  at  maximum.  Xo 
definite  reaction,  i.e.,  no  definite  sensation,  is  produced. 
After  a  Avait  of  a  few  minutes  the  test  is  again  applied, 
this  time  starting  with  the  current  controller  at  maxi- 
mum, and  now  there  is  a  definite,  unmistakable  reaction. 
The  tooth  did  not  respond  Avhen  touched  with  the  control- 
ler at  maximum  the  first  time  because  of  the  immunity  or 
tolerance  acquired  as  the  controller  was  gradually  ad- 
vanced. 

Fillings 

As  stated  elsewhere,  unless  there  is  a  sj)ot  of  sound 
enamel  to  which  the  dental  electrode  may  be  ai)plied,  the 
tooth  with  the  large  metal  filling  cannot  be  tested. 

Fillings  of  moderate  size  do  not  interfere  materially 
witli  the  application  or  accuracy  of  the  test.  Take  them 
as  a  class  of  teeth,  however,  and  it  will  be  found  that 
teeth  with  moderately  large  fillings  require  slightly  more 
current.  This  is  due  likely  to  the  fact  that  the  stimulus 
of  a  metal  filling  produces  secondary  dentin. 


80  ELECTRO-EADIOGEAPHIC    DIAGj^OSIS 

The  possibility  of  the  current  traveling  from  the  point 
of  application  of  the  dental  electrode,  through  the  tooth, 
into  a  metal  filling  and  through  it  into  an  approximating 
tooth,  the  gum  tissue  or  the  pericemental  membrane,  is 
undeniable.  But,  in  practice,  I  find  I  do  not  have  this 
trouble.  I  grant  that  such  a  thing  might — must — occur, 
but  in  practice  it  seems  not  to  occur  sufficiently  to  cloud 
diagnoses.  Eubber  dam  may  be  used  as  an  insulation  as 
previously  suggested,  if  desired.  When  I  first  started  to 
use  the  test  I  used  the  rubber  dam  insulation  frequently 
but  I  have  not  found  it  necessary  to  use  it  recently. 

The  possibility  of  the  current  traveling  from  the  point 
of  application  of  the  dental  electrode,  through  the  tooth, 
into  a  metal  filling,  through  it  into  a  metal  post  in  the 
canal  and  through  the  side  of  the  root  into  the  pericemen- 
tal membrane,  is  likewise  eminently  possible  from  a  theo- 
retic standpoint.  But  from  a  practical,  clinical  standpoint 
this  seems  not  to  occur;  thus  far  it  has  not  occurred  in  my 
jDractice,  except  once  where  the  post  extended  through  a 
perforation  in  the  side  of  the  root.  If  one  should  touch 
the  metal  of  a  large  filling,  or  unsupported  enamel  just 
over  metal,  sufficient  current  to  cause  pain  would 
promptly  reach  gum  tissue,  pericemental  membrane  or  an 
approximating  tooth;  but  this  would  be  a  violation  of 
correct  technic. 

Pericementitis 

A  tooth  with  a  dead  pul^D,  and  severe  pericementitis  is 
said  to  respond  to  the  electric  test  for  pulp  vitality.  From 
a  theoretic  standpoint  this  should  be  true  but  fortunately 
in  practice  it  seems  not  to  be.  In  my  own  practice  I  have 
never  been  misled  to  believe  a  pulp  vital  by  getting  posi- 
tive reaction  from  an  inflamed  pericemental  membrane. 
Pressure  against  the  tooth  transmitted  to  an  inflamed 
l^ericemental  membrane  will,  of  course,  cause  pain.     So 


STRENGTH    OF    CURRENT  81 

the  electrode  should  not  be  pressed  against  the  tooth. 
Make  a  moisture  contact  if  necessary  to  avoid  pressure. 

Differentiation  Between  Pulpal  and  Gin^val  Sensation 

Recently  1  was  testing  an  upper  right  second  molar 
with  a  large  filling.  The  tooth  was  very  short  occluso- 
gingivally.  The  only  spot  of  sound  enamel  to  which  the 
electrode  could  be  applied  was  on  the  mesio-lingual.  I 
started  with  the  current  low,  touching  the  tooth  at  inter- 
vals, and  advanced  the  current  controller  to  maximum. 
There  w^as  no  sensation  at  all  until  the  maximum  current 
was  used,  and  then  the  response  was  only  a  very  weak 
positive  (+VW).  As  I  have  said,  the  tooth  was  very 
short.  This,  coupled  with  the  very  weak  response  to  the 
maximum  current,  made  me  wonder  whether  the  response 
I  had  received  was  from  a  vital  pulp  or  whether  some  of 
the  current  had  leaked  into  the  gum. 

I  retarded  the  current  controller  to  almost  zero,  ap- 
plied the  electrode  to  the  enamel  on  the  mesio-lingual, 
then  slowly  pushed  the  point  of  the  electrode  toward  the 
gum  until  it  almost  touched  it,  when  the  j^atient  regis- 
tered sensation. 

I  said  to  the  patient:  "Did  that  feel  like  it  did  a  mo- 
ment ago,  when  I  touched  the  tooth  before?" 

The  patient  replied:  "Oh,  no.  This  last  was  different. 
It  was — ^well,  it  was  quite  different." 

Of  course  the  patient  did  not  know  that  the  first  sensa- 
tion was  caused  with  the  electrode  on  enamel  as  far  from 
the  gum  and  metal  filling  as  possible  and  with  the  cur- 
rent controller  at  maximum,  while  the  second  sensation 
was  produced  with  the  dental  electrode  forming  a  con- 
tact, by  moisture,  with  the  gum  tissue.  The  patient  knew 
none  of  the  details.  All  she  knew  was  that  the  second 
time  she  received  sensation  it  was  "Oh,  quite  different 
from  the  first." 


82  ELECTEO-EADIOGEAPHIC    DIAG^S'OSIS 

Because  of  the  difference  in  the  essential  nature  of  the 
sensation  proclnced  in  the  gum  tissue,  compared  to  that  at 
first  produced  by  touching  enamel,  I  deduced  that  the 
first  sensation  came  from  a  vital  pulp.  Radiographic 
findings  bore  me  out  in  this  opinion. 

This  is  the  only  case  in  which  I  have  tried  to  differ- 
entiate between  pulpal  sensation  and  gingival  sensation 
by  deliberately  moving  the  electrode  along  the  side  of 
the  tooth  to  an  electric  contact  with  the  gum.  The  pro- 
cedure gave  desirable  results  in  the  one  case  in  which 
it  was  tried  and,  it  seems  to  me,  it  gives  promise  of  con- 
siderable clinical  value  in  cases  where  the  operator  is  un- 
certain wdiether  the  sensation  he  produces  is  due  to  a 
vital  pulp  or  leakage  of  the  current  into  the  gum. 

I  have  found  also  that  when  there  is  a  sensation  pro- 
duced in  a  pulpless  tooth  by  a  slight  leakage  of  current 
into  a  large  metal  filling,  the  patient  will  often  say,  if 
questioned,  ''But  that  was  different  from  the  others," 
meaning  different  from  the  sensation  produced  in  other 
teeth  tested  in  which  the  pulps  were  vital. 

I  recall  the  old  question,  a  fine  one  to  argue  about  if 
you  like  to  argue:  ''Are  pain  and  touch  separate  and 
distinct  senses,  or  is  pain  simply  a  form  or  manifestation, 
a  sort  of  hyperesthesia,  of  the  sense  of  touch ?"  I  recall 
also  that  there  are  men  who  say  that  the  dental  pulp  has 
no  sense  of  touch,  only  the  sense  of  pain. 

I  do  not  open  these  old  questions  to  argue  them.  All 
I  wish  to  say  here  is  that  the  sensation  in  the  dental  pulp 
produced  by  the  electric  current  is  different,  sharper, 
than  that  produced  in  the  gum.  Of  course  a  considerable 
amount  of  current  in  the  gum  Avill  produce  a  "sharp" 
sensation. 


CHAPTER  VII 

LIMITATIONS 

Every  test,  everything,  for  that  matter,  has  its  limita- 
tions. The  most  outstanding  limitations  of  the  electric 
test  for  vitality  of  the  dental  pulp  are : 

(1)  Crowned  teeth  cannot  be  tested.  (One  must  con- 
tinue here  to  use  the  thermal  tests  which  the  electric  test 
so  nearly  displaces  altogether,  or  make  a  diagnostic 
opening.) 

(2)  Some  teeth  with  very  large  fillings  cannot  be  tested 
successfully.    Fortunately  there  are  not  many  such  teeth. 

(3)  In  multirooted  teeth,  where  the  pulp  in  one  canal  is 
vital  and  in  another  nonvital,  the  response  to  the  electric 
test  is  practically  the  same  (a  little  weak)  as  though  all 
parts  of  the  pulp  were  vital. 

(4)  One  is  doing  well  to  determine,  from  the  electric 
test,  simply  whether  the  pulp  is  vital  or  not.  Even  this 
cannot  always  be  done.  The  average  operator  (the  writer 
includes  himself  in  this  class)  will  find  it  impossible,  ex- 
cept in  the  rarest  cases,  to  diagnose  pathologic  states  of 
the  pulp  with  the  electric  test.  One  is  treading  on 
treacherous  ground  indeed  when,  after  applying  the  elec- 
tric test,  one  makes  bold  to  say,  ^'This  pulp  is  vital  and 
in  a  state  of  normality  or  health,  and  this  one  is  also  vital 
and  much  inflamed  with  pus  infiltration."  It  is  not 
practical. 

A  small  booklet  "Electro-Diagnosis  of  Diseases  of  the 
Pulp"  has  recently  come  to  my  attention.  It  is  published 
by  a  manufacturer  of  electric  pulp  testing  machines  and, 
in  the  main,  is  quite  a  worthy  little  essay  on  the  subject 
of  testing  pulps  for  vitality  with  electricity.  However, 
the  idea  of  diagnosing  pulp  diseases — not  simply  deter- 

83 


84  ELECTEO-EADIOGEAPHIC    DIAGNOSIS 

mining  Avlietlier  the  pulp  is  vital  or  not,  but  diagnosing 
pnlp  diseases — seems  rather  "far  fetched."  I  quote  the 
following  : 

"The  following  scheme  may  serve  as  a  guide  for  mak- 
ing a  diagnosis:  1.  The  normal  pulp  responds  to  the  cur- 
rent at  the  irritation  point.  2.  The  irritated  pulp  re- 
sponds to  the  current  at  the  irritation  point,  or  just 
slightly  below  it.  3.  The  inflamed  pulp  responds  to  the 
current  below  the  normal  irritation  point.  The  more  se- 
vere the  inflammation,  the  more  ready  the  response  to 
the  current.  4.  The  inflamed  pulp  with  pus  infiltration 
(abscess  formation)  responds  to  the  current  above  the 
normal  irritation  jDoint.  The  more  severe  the  purulent 
condition,  the  less  read}'"  the  response  to  the  current.  5. 
The  dead  pulp  does  not  respond  at  all,  not  even  to  the  full 
strength  of  the  current." 

My  advice  to  anyone  Avho  reads  the  foregoing  is  to  dis- 
regard it.  If  3^ou  do  not  it  seems  to  me  it  will  confuse  you 
hopelessh^  Do  not  tiy  to  diagnose  diseases  of  the  pulp 
with  the  electric  test;  tiy  onl^^  to  learn  whether  or  not 
the  pulp  is  vital. 

Do  not  think  that  one  type  of  pulp  testing  machine  Avill 
enable  you  to  gain  such  perfect  results  that  you  can  diag- 
nose pulj)  disease,  while  other  t^^pes  of  machines  enable 
3^ou  onl}^  to  ascertain  whether  the  pulp  is  vital.  It  is 
the  nature  of  the  test  itself,  not  the  nature  of  the  i)ulp 
testing  machine,  that  makes  such  fineness  of  diagnosis  as 
outlined  above  impossible. 

I  quote  from  the  above:  "The  inflamed  pulp  responds 
to  the  current  below  the  normal  irritation  point.  The 
more  severe  the  inflammation,  the  more  ready  the  re- 
sponse to  the  current." 

Quite  true,  an  inflamed  pulp  reacts  more  shari^ly  and  to 
less  current  than  a  normal  pulp.  But  suppose  Ave  have 
the  combination  of  an  inflamed  jDulp  and  secondary  den- 
tin— a  not  at  all  unusual  combination?    It  takes  less  cur- 


LIMITATION'S  85 

rent  to  reach  tlie  irritation  point  of  an  inflamed  pnlp,  bnt 
it  takes  more  current  to  reach  the  irritation  point  in  a 
case  of  secondary  dentin.  So  if  we  have  both  an  inflamed 
pnlp  and  secondary  dentin,  the  one  condition  may  can- 
cel the  other  and  the  inflamed  pnlp  react  like  a  normal 
one. 

I  cjnote  again:  "The  inflamed  pnlp  with  pns  infiltration 
(abscess  formation)  responds  to  the  cnrrent  above  the 
normal  irritation  jDoint.  The  more  severe  the  pnrnlent 
condition,  the  less  ready  the  response  to  the  cnrrent." 

A  semivital  pnljD  reacts  less  sharply  and  requires  more 
current  than  a  normal  jDulp.  But  suppose  the  dental  elec- 
trode is  applied  to  a  spot  on  the  tooth  where  the  enamel 
is  quite  thin.  Then  the  semivital  pulp  may  react  like  a 
normal  pulp. 

One  might  continue  citing  case  after  case  ad  iufinitiim 
to  demonstrate  the  futility  of  lioj)ing  to  diagnose  pulp 
disease  with  the  electric  test.  Just  a  word  further  though. 

Let  us  imagine  we  stand  Avatching  an  operator  apply 
the  electric  test.  Suddenl}^  he  gets  a  severe  reaction,  the 
patient  jumps  violently,  though  the  current  used  was  no 
stronger  than  that  used  on  several  adjoining  teeth.  Ah ! 
he  has  touched  a  tooth  with  an  inflamed  pulp!  But  has 
he!  Perhaps,  instead,  the  dental  electrode  has  been  ap- 
plied to  unsupported  enamel,  or  to  a  metal  filling,  or  it 
has  come  too  near  the  gum,  or  it  has  touched  a  sjiot  of 
thin  enamel  or  exposed  dentin,  or  perhajDS  the  current  has 
traveled  through  moisture  into  a  gum-covered  carious 
cavity  or  into  a  fault  in  the  enamel  such  as  a  fissure  or 
pit.  But  are  we  not  agreed  that  the  electric  test  is  a 
means  of  determining  pulp  vitality,  not  a  means  of  diag- 
nosing pulp  diseases  ? 


CHAPTER  VIII 

APPLYING  THE  TEST  FOR  NERVOUS  PATIENTS 

Electropliobia  (fear  of  electricity)  is  universal.  As 
stated  in  Chapter  VI  practically  all  liuman  beings  are 
afflicted;  there  is  difference  merely  in  degree. 

When  the  electric  test  is  suggested  many  patients  will 
offer  strenuous  objections  saying  ''I  cannot  stand  elec- 
tricity. ' ' 

The  Psychology  of  the  Situation 

Before  the  operator  proceeds  with  the  application  of 
the  test  he  should  take  into  account  this  mental  attitude 
of  the  patient  and  try  to  overcome  any  undue  anxiety  or 
fear. 

The  test  is  not  accompanied  with  sufiflcient  pain  for  any- 
one who  knows  what  it  is  like  to  dread  it.  But  the  oper- 
ator must  not  lose  sight  of  the  fact  that  his  patient  may 
not  have  the  slightest  idea  of  what  the  test  is  like  and 
imagine  it  very  dreadful.  The  handling  of  this  situation 
will  vary  with  different  patients,  but  is  fundamentally 
the  same  in  all  cases. 

The  psychologic  problem  is  a  comparatively  easy  one 
and  is  simply  that  of  removing  or  lessening  excessive  fear 
of  the  unknown. 

Test  Harmless 

When  the  patient  fears  that  some  permanent  injury 
may  be  done  the  teeth  by  the  test  one  cannot  be  too  em- 
phatic in  assuring  such  a  patient  that  no  harm  will  be 
done.    The  fact  is  that  the  test  is  absolutely  harmless. 

Let  us  imagine  we  are  applying  the  test  in  the  case  of  a 
particularly  nervous  patient. 


APPLYIISTG    TEST    IN"    NERVOUS    PATIENTS  0< 

A  Sort  of  Written  Clinic 

Tlie  conversation  given  hereinafter  is  subject  to  great 
variation.  It  is  not  intended  as  a  verbatim  account  of 
what  should  be  said.    It  is  a  sort  of  written  clinic. 

We  proffer  the  patient  the  hand  electrode  asking  him 
to  take  it.  He  pushes  it  away  or  takes  it  testily,  saying, 
''What's  that!" 

We  say  something  like  this:  "Don't  be  afraid;  you  will 
not  feel  anything  in  your  hand ;  you  will  not  feel  anything 
at  all  anywhere  until  I  tell  you  about  it.  Take  it. ' '  We 
hand  the  electrode  to  him,  often  closing  his  fingers  over 
it  as  we  speak. 

With  the  patient  holding  the  electrode  we  continue, 
' '  Now  we  want  to  test  your  teeth  to  see  whether  the  pulps 
are  vital." 

"What  is  it?  Electricity?  I  can't  stand  electricity!" 
This  from  the  patient. 

"It  will  not  feel  like  electricity.  You  will  not  feel  it 
in  your  hand  at  all  you  know,  and  whether  you  can  feel  it 
in  your  tooth  or  not  is  what  we  want  to  find  out.  If  you 
feel  it  in  your  tooth  at  all  it  won't  feel  like  electricity. 
There  will  be  just  a  little  sting  (like  when  you  are  having 
a  tooth  prepared  for  a  filling,  only  not  nearly  so  severe). 

"We  touch  the  tooth  only  for  a  moment,  see,  like  this." 
The  operator  touches  his  own  fingernail  Avith  the  dental 
electrode  and  removes  it  two  or  three  times  to  demon- 
strate that  the  application  of  the  electrode  to  the  teeth  is 
only  momentary. 

"You  are  not  to  even  tri/  to  stand  any  pain.  We  want 
you  to  tell  us — flinch  or  say  'huh' — just  as  soon  as  you 
feel  it  tingle  the  least  bit.  This  is  different  from  any 
other  kind  of  dental  work;  you  see  we  can  stop  as  soon  as 
you  feel  it.  There 's  nothing  more  to  do  then,  nothing  we 
have  to  do  whether  it  hurts  or  not. ' ' 

"We  Avill  start  Avith  the  current  so  weak,  you  Avill 
hardly  feel  it,  if  you  feel  it  at  all." 


88  ELECTEO-EADIOGEAPHIC    DIAGXOSIS 

As  iDrevioiis]}^  stated,  wlien  tlie  machine  lias  three 
sockets  or  binding  posts,  I  use  the  tester  ahvays  with 
the  cords  plugged  into  L  and  R  (1-3) .  It  is  very  anno^dng 
and  impractical  to  make  changes  in  connections  to  modify 
the  current  strength.  So  with  the  cords  plugged  into  L-R, 
and  the  current  regulator  at  minimum  we  are  ready  to 
demonstrate  the  truth  of  our  assertion  to  the  patient  that 
the  test  can  he  applied  with  the  current  so  weak  it  will 
scarcely  be  felt,  if  felt  at  all. 

Since  we  are  keeping  our  j^lugs  in  L-R  (1-3)  our  cur- 
rent is  not  as  weak  as  it  could  be  made,  not  as  weak  as 
it  would  be  in  L-M  (1-2)  or  M-R  (2-3)  and  so  we  must 
resort  to  some  means,  other  than  the  changing  of  plugs, 
to  keep  our  current  sufficiently  weak.  (In  this  connection 
it  must  be  conceded  again  that  there  are  some  Faradic 
machines  which  simply  give  too  strong  a  current  to  keep 
the  plugs  in  L-R  (1-3).) 

This  may  be  done  as  follows :  Dip  the  cotton-wrapped 
end  of  the  dental  electrode  in  water  or  the  sodium  chlorid 
solution,  then  exjDel  all  the  moisture  from  the  cotton  again 
by  pressing  it  against  a  piece  of  white  blotting  paper  or 
a  napkin.  Thus,  if  the  patient  is  observing  our  actions, 
he  sees  us  go  through  the  same  procedure  ordinarily  fol- 
lowed, except — and  it  is  very  unlikely  that  he  will  notice 
this — we  press  the  moistened  cotton  against  the  blotting- 
paper  expelling  practically  all  moisture,  instead  of  simply 
toucldng  the  blotting  jDaper  to  take  up  excessive  mois- 
ture. With  the  cotton  on  the  electrode  dry,  or  almost  dry, 
it  is  not  a  good  conductor,  so  when  applied  to  a  tooth  only 
slight  sensation,  if  any,  is  produced. 

If  the  machine  can  be  graded  to  zero  by  the  current 
regulator,  all  this  is  unnecessary. 

Usually,  as  soon  as  the  patient  learns  that  a  tooth  can 
be  touched  with  the  dental  electrode  without  producing 
extreme  pain,  their  excessive  fear  is  gone. 


APPLYIIv^G    TEST    I]^    aSTERVOUS    PATIENTS  89 

Just  as  soon  as  the  patient  registers  liaving  received 
sensation — by  sound  or  flinching — stop  and  say,  "Now 
you  know  what  it  is  like — you  know  all  about  it." 

The  Imperfect  Moisture  Contact 

The  trick  (or  expedient,  if  you  like  the  longer  word 
better)  of  making  the  imperfect,  moisture  contact  is  of 
the  utmost  value.  It  would  be  impossible  to  test  teeth, 
and  get  reliable  results,  for  some  nervous  patients  if  it 
were  not  for  this  "stunt  in  technic."  For  a  description 
of  the  technic  of  making  this  contact  see  Chapter  V  under 
the  heading  "A  Valuable  Point  in  Technic." 

Only  a  Few  Patients  Difficult  to  Handle 

I  regret  having  failed  to  make  my  consideration  of  the 
handling  of  patients  shorter.  I  fear  I  may  lead  my  read- 
ers to  believe  the  application  of  the  electric  test  is  always 
attended  with  considerable  difficulty  and  the  necessity 
for  much  explanation,  which  is  not  the  case. 

Offer  No  Explanations  or  Comments  Unless  Necessary 

The  foregoing  is  calculated  to  teach  the  beginner  to 
meet  any  emergency  which  may  arise.  Let  it  be  clearly 
understood  that  it  is  not  advisable  to  give  any  sort  of  ex- 
planation to  a  patient  unless  the  patient's  state  of  mind 
is  such  as  to  make  it  necessary.  A¥hen  the  patient  is 
not  afraid  it  is  obviously  unnecessary  to  take  steps  to  re- 
lieve fear.  Indeed  such  a  course  would  create  fear  where 
it  had  not  existed.  Talk  to  the  patient  about  the  test  as 
little  as  possible,  but  as  much  as  necessary.  As  the  oper- 
ator becomes  more  skillful  in  the  use  of  the  test  he  will 
find  less  need  for  conversation  with  his  iDatient  regarding 
it. 


90  ELECTRO-RADIOGRAPHIC    DIAGNOSIS 

Children 

As  far  as  possible  I  treat  cliildren  as  tliougli  they  were 
grown-ups.  The  most  notable  exception  is  to  say  to  a 
good  natured,  unafraid  child  something  like  this:  "Now 
this  thing  will  tickle  a  little  bit.  I  want  you  to  tell  me 
Avlien  you  feel  it  start  to  tickle  and  I'll  stop.  I  just  want 
to  see  if  your  teeth  are  alive  by  finding  out  if  they  are 
ticklish."  The  use  of  the  word  ''tickle"  has  a  splendid 
psychologic  effect,  and  if  the  operator  is  careful  he  need 
cause  no  more  sensation  than  the  child  will  accept  as 
''ticklish."  If  the  child  is  too  ill-natured  or  too  afraid, 
this  effort  at  suggestion  will  fail,  but  it  usually  "works" 
beautifully. 


CHAPTER  IX 

ANSWERING  ADVERSE  CRITICISM 

Comparatively  little  has  been  Avritten  on  the  subject  of 
tlie  electric  test  for  pulp  vitality.  What  has  been  written 
has  been  by  men  who  use  the  test  and  believe  in  its  effi- 
ciency. Scarcely  anything  at  all  has  been  written  in  the 
way  of  constructive  criticism,  indeed  hardly  anything  at 
all  has  been  written  in  the  way  of  any  sort  of  criticism. 

Verbal  criticism,  hoAvever,  is  not  at  all  uncommon. 

The  only  thing  I  am  able  to  locate  just  now  in  the  way 
of  adverse  criticism  appeared  in  Dental  Cosmos,  October, 
1918.  I  quote  from  this  article:  ''At  a  clinic  all  hands 
agreed  that  a  certain  tooth  appeared  to  be  devitalized. 
The  pulj)  tester  was  applied,  and  it  gave  positive  and  un- 
mistakable signs  that  the  pulp  was  vital.  A  skiagraph 
was  then  taken,  Avhich  showed  that  the  roots  were  filled ! ' ' 

Such  reports  as  these  fail  utterly  to  convince  or  even 
to  approach  convincing  the  writer  of  the  inadequacy  of 
the  electric  test,  for  I  ask  myself  such  questions  as  these : 
Did  the  operator  touch  a  metal  filling?  Did  the  operator 
touch  the  gum  tissue?  Did  the  operator  touch  unsup- 
ported enamel?  Did  the  operator  use  the  wrong  kind  of 
a  dental  electrode  and  touch  the  patient's  lij)  or  cheek? 
Was  the  patient  so  nervous  that  he  jumped  without  re- 
ceiving sensation?  Was  the  tooth  sore  and  was  the  elec- 
trode pressed  against  the  sore  tooth  thus  causing  pain? 
Was  the  tooth  covered  with  moisture  and  did  the  current 
travel  through  the  moisture  to  an  adjoining  tooth!  In 
short,  did  the  operator  know  how  to  apply  the  test,  for 
certainly  the  inefficiency  of  a  test  is  not  proved  when  it 
is  applied  by  an  inefficient  operator  ? 

91 


92  ELECTRO-EADIOGRAPHIC    DIAGIS'OSIS 

I  quote  again  from  the  article  referred  to  above.  It 
being  the  onl}''  written  thing  I  have  to  attack,  let  me  at- 
tack it  in  several  places.  I  quote  the  following  as  an  ex- 
ample of  bad  logic:  "He  was  asked,  'Is  the  electrical 
test  always  positive!'  He  answered,  'No.'  To  the  query, 
'Is  the  thermal  test  always  positive?'  he  replied  'No.' 
To  the  question,  'Then  in  a  final  analysis  the  only  real 
way,  in  this  the  year  1918,  to  tell  whether  or  not  a  pulp 
is  dead  or  alive  is  to  drill  into  iff  the  answer  Avas  'Yes.' 

"And  there  3^ou  are!" 

Following  this  sort  of  reasoning  one  might  claim  that 
"the  onh^  real  way"  to  iDrevent  insanity  is  to  cut  off  the 
head.  An  autopsy  is  a  "real  way"  of  making  a  diagnosis 
but  it  is  destined  to  remain  a  sort  of  a  last  resort. 

There  are  some  teeth,  the  vitality  of  the  pulps  of  which 
cannot  be  determined  except  by  making  a  diagnostic 
opening,  but  there  are  millions,  millions  upon  millions, 
the  vitality  of  the  pulps  of  which  can  be  determined  by 
the  electric  test,  or  by  the  electric  test  and  the  making 
of  a  radiograph. 

AVhile  written  criticisms  of  the  test  are  scarce,  verbal 
ones,  as  I  have  said,  are  far  from  scarce.  Here  is  a  typi- 
cal verbal  one,  addressed  to  me  recently  by  one  of  my 
friends:  "I  applied  the  electrode  to  a  simple  occlusal 
filling  and  the  reaction  was  positive  and  definite.  I 
opened  the  tooth  and  found  the  pulp  putrescent." 

I  have  no  reason  whatever  to  doubt  the  truth  of  such 
statements,  but  let  us  take  a  case  such  as  the  one  just 
mentioned  and  apply  our  electric  test  before  making  a 
radiograph,  making  records  of  the  application  of  the 
electric  test.  We  will  supj)ose  it  is  a  lower  first  molar. 
It  is  my  custom  to  test  at  least  the  two  teeth  approxi- 
mating the  tooth  under  examination.  So,  then,  we  test 
the  second  bicuspid  and  the  second  molar  and  find  that 
both  of  them  respond.  We  test  the  first  molar,  applying 
the  electrode  to  the  enamel  and  find  that  it  does  not  re- 


ANSWERING    ADVERSE    CRITICIS:\r  93 

s23ond.  Accordingly,  we  make  the  current  weaker  and 
slide  the  electrode  on  to  the  metal  of  the  occlusal  filling; 
and  let  ns  imagine  that  still  the  tooth  does  not  respond. 
We  increase  the  current  and  now  we  get  a  response. 

Under  such  circumstances  shall  we  simply  mark  our 
chart  positive  for  the  first  molar  I  By  no  means,  I  would 
mark  such  a  tooth  ''positive  questionable"  (+!)  or  per- 
haps make  a  special  note  under  "remarks"  saying  "Pos- 
itive on  amalgam  filling,  negative  on  enamel. ' ' 

Such  records  then  would  cast  suspicion  ujoon  this  tooth. 

Suppose  now  we  go  ahead  and  make  a  radiograph  and 
we  find  the  metal  filling  running  to,  or  perhaps  slightly 
into,  the  puljD  chamber.  AVe  also  find  a  very  slight  bone 
change,  a  slight  osteoclasia,  and  a  suggestion  of  osteo- 
sclerosis, at  the  apex  of  one  of  the  roots.  This  bone 
change  is  not  sufficient  in  itself  to  be  taken  as  an  indica- 
tion of  periapical  infection  but  couj)led  with  the  other 
evidence  we  have  gathered — manner  of  response  to  the 
electric  test  and  the  metal  filling  penetrating  deeply  to- 
ward the  pulj) — this  bone  change  may  be  taken  as  further 
evidence  that  the  pulp  is  probably  not  vital.  (The  course 
of  the  current  to  produce  sensation  could  be  through  the 
amalgam  filling,  through  the  moisture  in  the  septic 
canals,  out  the  apical  foramina  to  vital  tissue.) 

With  such  an  arra}^  of  evidence  indicating  a  nonvital 
pulp  certainly  any  diagnostician,  worthy  of  the  name, 
AYould  suspect  a  dead  pulp,  even  if  there  was  response 
upon  the  aiDj^lication  of  the  dental  electrode  to  the  metal 
filling. 

It  just  occurs  to  nie:  I  did  not  ask  my  friend  why  he 
opened  the  tooth.  Perhaps  he  took  into  account  some  of 
the  things  I  have  mentioned,  or  perhaps  subjective  symp- 
toms were  such  as  to  cause  him  to  open  the  tooth.  And 
this  reminds  me  to  give  warning  that  the  electric  test  is 
not  intended  to  take  the  place  of  all  other  diagnostic 
measures.    Symptoms  should  be  considered,  of  course. 


94  ELECTRO-EADIOGEAPHIC    DIAGNOSIS 

Everything  considered:  Tlie  inadequate  dental  elec- 
trodes which  have  been  used.  The  inadequate  machines 
also.  The  erroneous  idea  that  the  technic  for  electric 
pulp  testing  requires  almost  no  knowledge  or  skill,  that 
the  entire  subject  is  covered  in  the  eight  fundamental 
steps  in  technic  set  forth  in  Chapter  IV,  in  less  than  five 
hundred  words.  The  unwillingness  to  accord  the  test  and 
its  technic  sufficient  respect.  I  say,  everything  consid- 
ered, the  wonder  is  not  that  some  men  attack  the  test  but 
that  it  is  as  popular  as  it  is. 


CHAPTER  X 

CLINICAL  VALUE  OF  THE  TEST 

There  are  many  sorts  of  cases  in  which  the  electric  test 
for  pnlj)  vitality  may  be  applied  to  great  advantage  by 
the  diagnostician.  It  is  not  jDossible  to  mention  all  the 
circumstances  nnder  Avhich  its  application  Avill  prove 
helpful,  and,  if  it  were,  the  mere  mention  of  such  circum- 
stances and  cases  w^ould  fail  to  impress  the  reader  or 
teach  him  so  effectively  as  the  illustrated  description  of 
cases. 

Nevertheless,  some  written  effort  to  indicate  the  extent 
of  the  value  of  the  test  seems  necessary  and  is  set  forth 
in  this  chapter.  To  get  a  fuller  realization  of  the  clinical 
status  of  the  test,  see  the  illustrations  in  the  next  chapter. 

The  following  is  a  list  of  cases  and  circumstances  in 
which  and  under  which  the  test  may  be  used  to  advan- 
tage: 

(1)  In  cases  of  systemic  disease  to  determine  which 
teeth  are  most  suspicious.  (2)  Where  no  x-ray  machine 
is  available.  (3)  To  check  all  x-ray  findings.  (4)  To  find 
teeth  wdth  dead  pulps  which  could  not  be  found  by  any 
other  means.  (5)  To  find  abscesses  which  might  other- 
wise be  overlooked  because  they  fail  to  show  in  radio- 
graphs made  at  certain  angles.  (6)  To  assist  in  recog- 
nizing very  slight  osteoclasia.  (7)  To  avoid  mistakes 
when  the  end  of  a  root  and  an  abscess  cavity  (with  no 
connection  between  the  two)  overlap  in  the  radiograph 
due  to  the  angle  at  which  the  exjDOsure  is  made.  (8)  To 
avoid  misinterpretation  when  the  abscess  cavity  laps  to 
the  lingual  or  facial  of  the  adjacent  teeth.  (9)  To  differ- 
entiate between  the  mental  foramen  and  an  abscess  cav- 
ity.    (10)  To  differentiate  between  the  anterior  j^alatine, 

95 


96  ELECTRO-RADIOGEAPHIC    DIAG^STOSIS 

or  incisive,  foramen  and  an  abscess  cavity.  (11)  To  dif- 
ferentiate between  tlie  antrum  of  Higlimore  and  an  ab- 
scess cavity.  (12)  To  differentiate  between  the  somewhat 
radiolncent  area  which  sometimes  appears  in  the  apical 
region  of  upper  lateral  incisors,  due  to  the  canine,  or  in- 
cisal,  fossae,  and  radiolucence  caused  by  infection  and 
pathologic  bone  change.  (13)  To  differentiate  between 
nostril  spots  and  abscesses.  (14)  To  aid  in  the  recogni- 
tion of  nasal  fossae  spots  as  such.  (15)  To  aid  in  the  rec- 
ognition of  the  inferior  dental  canal  as  such.  (16)  To 
differentiate  between  a  very  small  abscess  cavity  and  an 
unusually  large  periapical  space.  (17)  To  differentiate 
between  a  cancellous  spot  of  unusual  appearance  and  an 
abscess  cavity.  (18)  To  assist  in  differentiation  between 
pathologic  and  physiologic  conditions  about  the  buccal 
roots  of  the  upi)er  molars.  (19)  To  assist  in  differentia- 
tion between  an  absorbed,  roughened  root  and  a  radio- 
graph made  Avith  the  rays  directed  through  the  tooth 
diagonally  from  facial  to  lingual.  (20)  To  differentiate 
between  partially  formed  root  and  an  abscess.  (21)  To 
determine  how  many  teeth  are  involved  in  an  abscess. 
(22)  To  assist  in  differentiation  between  dentoalveolar 
abscess  and  periodontoclasia  (pyorrhea). 

1.    In  Cases  of  Systemic  Disease  to  Determine  Which 
Teeth  Are  Most  Suspicious 

The  determination  of  which  teeth  are  most  suspicious 
aids  in  many  ways.  If  the  cost  of  examination  is  to  be 
cut  to  the  minimum  those  teeth  which  respond  perfectly 
to  the  test  need  not  be  radiographed.  And  even  if  all  of 
the  teeth  are  to  be  radiographed,  those  which  respond  to 
the  electric  test  need  not  be  radiographed  or  studied  with 
such  care  as  those  which  cannot  be  tested  or  test  neg- 
ativel}^  Thus  the  number  of  negatives  it  is  necessary  to 
make  is  reduced  and  at  the  same  time  the  operator's  at- 


CLINICAL   VALUE    OF    THE    TEST  97 

tention  is  directed  to  tliose  parts  where  make-overs  are 
most  likely  to  be  indicated. 

It  is  always  tlie  part  of  wisdom  to  avoid  unnecessary 
x-ray  exposure,  and  in  some  emergency  cases  where  the 
operator  hajipens  to  be  operating  Avith  inadequate  pro- 
tection this  is  especially  true. 

Much  has  been  said  of  x-ray  pictures  relieving  the  den- 
tal operator  of  the  necessity  of  working  in  the  dark.  The 
electric  test  relieves  the  x-ray  operator  himself  from  the 
handicap  of  working  in  the  dark  and  so  enables  him  to 
make  a  better  examination. 

In  cases  of  systemic  disease  examination  of  the  mouth 
for  infection  is  made  in  one  of  three  Avays :  (1)  All  teeth 
and  all  parts  of  the  mouth  are  radiographed.  (2)  All 
teeth  which  do  not  react  positively  to  the  electric  test,  or 
cannot  be  tested,  all  regions  from  which  teeth  are  miss- 
ing, and  all  teeth  affected,  or  thought  to  be  affected,  with 
pyorrhea  and  all  regions  of  unusual  appearance  are  radio- 
graphed. (3)  The  teeth  which  react  negatively  and  those 
which  cannot  be  tested  are  radiographed. 

For  the  reasons  already  given,  the  writer  applies  the 
electric  test  even  if  all  the  teeth  are  to  be  radiographed 
and  whether  it  is  permissible  to  eliminate  parts  of  the 
mouth  from  the  necessity  of  examination  at  all  or  not  de- 
pends on  two  things:  The  operator's  judgment  and  the 
electric  test. 

When  the  examination  is  for  iDulpless  and  abscessed 
teeth  only,  those  regions  in  which  the  teeth  respond  per- 
fectly and  positively  to  the  test  need  not  be  radiographed. 
When  the  examination  is  more  inclusive,  such  regions 
may  be  radiographed  and  may  reveal  such  lesions  as  ca- 
rious cavities,  overhanging  fillings,  incipient  iiyorrhea, 
odontomata,  and  supernumerary  teeth. 

Where  we  speak  of  the  application  of  the  test  Ave  as- 
sume that  its  api^lication  is  made  in  a  competent,  intelli- 


98  ELECTRO-RADIOGRAPHIC    DIAGNOSIS 

gent  manner,  for  nnless  this  is  the  case,  the  electric  test, 
like  all  tests  under  similar  circumstances,  is  useless. 

2.  Where  No  X-Ray  Machine  Is  Available 

Where  no  x-ray  machine  is  available  the  only  way  to 
determine  which  teeth  are  pulpless  with  any  degree  of 
accuracy  is  to  use  the  electric  test.  This  will,  in  most 
cases,  enable  the  operator  to  locate  the  pulpless  teeth 
quite  successfully.  A  friend  who  ''believes  in  the  ex- 
traction of  all  pulpless  teeth"  maintains  that  the  deter- 
mination of  which  teeth  are  pulpless  is  all  that  is  neces- 
sary and  that  if  this  can  be  done  with  the  electric  test 
then  radiographs  are  unnecessary.  He  fails  to  consider 
the  value  of  the  radiograph  to  verify  his  electric  test  find- 
ings and,  further,  the  radiograph,  by  showing  the  amount 
of  bone  destruction,  assists  in  curettement,  so  it  helps 
even  the  extreme  extractionist.  It  is  necessary  to  remove 
shell  crowns  before  the  teeth  carrying  them  can  be  tested. 

Where  we  have  the  combination  of  a  seriously  sick  pa- 
tient and  no  x-ray  machine  available,  the  test  may  be  used 
to  locate  the  pulpless  teeth.  Thus  extraction  of  teeth  with 
vital  pulps  may  be  avoided  and  at  the  same  time  all  peri- 
apical infection  is  eliminated. 

3.  To  Check  All  X-Ray  Findings 

Both  the  electric  test  and  the  radiograph  are  quite  sus- 
ceptible to  error — to  misinterpretation  let  us  say — but 
taken  together,  letting  the  one  check  the  other,  chance  for 
error,  if  not  entirely  eliminated,  is  reduced  to  an  agree- 
able minimum. 

The  writer  started  to  use  the  electric  test  in  his  practice 
of  radiodontia  in  selected  cases  and  came  gradually  to 
use  it  in  all  cases.  It  is  my  practice  now  to  apply  the  test 
first,  in  all  cases  where  radiographs  are  to  be  made,  and 
to  make  records  of  the  results  of  the  application  of  the 


CLINICAL   VALUE    OF    THE    TEST  99 

test  on  the  chart  innstratecl  in  Fig.  22.  From  the  records 
on  the  electric  test  chart,  the  recorded  history  of  the  case, 
and  the  finislied,  mounted  radiographic  negatives,  a  diag- 
nosis and  prognosis  are  given. 

In  cases  where  a  tooth  is  suspected  of  being  pulpless  or 
abscessed  and  an  x-ray  examination  is  to  be  made  of  such 
a  tooth  I  make  it  an  invariable  rule  to  test  at  least  the 
two  teeth  approximating  the  one  under  examination. 

4.  To  Find  Teeth  with  Dead  Pulps  Which  Could  Not  be 

Found  by  Any  Other  Means 

A  tooth  Avitli  (as  yet)  no  periapical  bone  change,  or 
filling  material  in  the  pulp  chamber  or  canals  that  has  a 
dead  iduIjd  cannot  be  located  by  means  of  radiographs. 
Such  teeth  may  be  found  by  the  use  of  the  electric  test. 
When  the  symptoms  (there  may  or  may  not  be  symptoms) 
are  such  as  to  place  a  certain  tooth  under  suspicion  the 
electric  test  ivill  assist  in  diagnosis. 

5.  To  Find  Abcesses  Which  Might  Otherwise  be  Over- 
looked Because  They  Fail  to  Show  in  Radiographs 

Made  at  Certain  Angles 

Let  us  consider  a  hypothetic  case,  the  like  of  which  is 
frequently  met.  A  radiograph  is  made  of  a  certain  tooth. 
It  shows  no  abscess  and  no  canal  filling,  but  the  electric 
test  for  this  tooth  is  negative.  Also  jDerhaps  there  are 
abscess  symptoms,  a  fistula  in  the  vicinity.  Another  ra- 
diograph is  made  at  a  different  angle  and  shows  osteo- 
clasia. Thus  an  abscess  cavity  is  found  which,  had  it  not 
been  known  that  the  tooth  did  not  have  a  vital  pulp, 
would  have  been  overlooked. 

Foreshortening  of  the  upj^er  teeth  may  result  in  the 
failure  of  an  existing  abscess  cavity  to  show.  Slight 
elongation  is  sometimes  advantageous;  it  enables  the 
operator  to  see  abscess  cavities  which  might  otherwise  be 
overlooked. 


100  ELECTKO-RADIOGRAPHIC    DIAGNOSIS 

6.  To  Assist  in  Recognizing  Slight  Osteoclasia 

An  area  of  osteoclasia  may  be  so  small  that  one  is  un- 
able to  say  definitely  whether  it  is  really  osteoclasia  or 
not.  In  such  cases,  whether  the  pnlp  is  vital  or  not  may 
be  the  deciding  factor.  If  the  pnlp  is  vital,  of  course  the 
suspicious  area  is  not  a  bone  change  due  to  infection,  but 
if  the  pulp  is  not  vital,  a  suspicious  area  can  be  classed 
as  osteoclasia  due  to  infection,  especially  if  there  is  some 
osteosclerosis  also. 

7.  To  Avoid  Mistakes  When  the  End  of  a  Root  and  An 

Abscess  Cavity  (With  No  Connection  Between  the 

Two)  Overlap  in  the  Radiograph  Due  to  the 

Angle  at  Which  the  Exposure  Is  Made 

When  a  tooth  seems  to  be  involved  in  an  abscess,  but 
responds  to  the  electric  test,  it  is  sometimes  possible  to 
make  radiographs  at  different  angles  which  will  show 
that,  after  all,  the  suspected  tooth  is  not  involved  in  the 
abscess  cavity.  If  a  root  end  is  more  or  less  surrounded 
by  an  abscess  cavity  it  will  register  in  radiographs,  if  at 
all,  at  the  end  of  the  affected  tooth.  But  if  the  abscess 
cavity  is  at  the  side  of  the  root,  and  the  root  end  only  ap- 
pears to  be  involved  in  the  abscess  due  to  the  angle  of  the 
x-rays,  a  shadow  of  the  abscess  cavity  can  usually  be  cast 
on  the  film  aw^ay  from  the  root  end. 

The  electric  test  thus  indicates  the  expediency  of  mak- 
ing more  radiographs  at  different  angles  in  such  cases 
and  keeps  the  operator  from  accepting  false  radiographic 
evidence.    See  Figs.  69  and  70. 

Abscesses  arising  from  the  lingual  roots  of  upper  bi- 
cuspids not  infrequently  have  the  radiographic  appear- 
ance of  involving  the  cuspid  and  lateral  incisor.  This  ap- 
pearance of  involvement  in  the  radiograph  may  be  due 
to  actual  lapping  of  the  abscess  cavity  to  the  lingual  of 
the  cuspid  or  lateral  or  may  be  due  to  the  angle  at  which 
the  exposure  is  made. 


CLINICAL   VALUE    OF    THE    TEST  101 

8.  To  Avoid  Misinterpretation  When  the  Abscess  Cavity 
Laps  to  the  Lingual  or  Facial  of  the  Adjacent  Teeth 

It  is  possible  for  an  abscess  cavity  to  lap  to  the  lingual 
or  facial  of  the  roots  of  the  adjacent  teeth  in  such  man- 
ner that  healthy  teeth  have  the  appearance  of  being  in- 
volved in  the  abscess.  In  such  cases  the  electric  test  is 
often  the  deciding  factor  and  so  of  the  utmost  importance. 

This  lapping  of  an  abscess  cavity  is  most  likely  to  oc- 
cur to  the  lingual  in  the  upper  teeth.  Cysts,  as  well  as 
abscesses,  may  lap  to  the  lingual  or  facial  of  healthy,  un- 
involved  teeth. 

9.  To  Differentiate  Between  the  Mental  Foramen  and  an 

Abscess  Cavity 

The  fact  that  the  mental  foramen  may  have  the  appear- 
ance of  being  an  abscess  of  the  first  or  second  (usually 
second)  lower  bicuspid  has  become  common  knowledge. 
Such  common  knowledge  in  fact  that  the  writer  has  seen 
an  abscess  cavity  mistaken  for  the  mental  foramen! 

Where  the  electric  test  can  be  applied  and  is  positive, 
the  operator  may  know  that  a  radiolucent  area  at  the 
apex  of  a  lower  bicuspid  is  the  mental  foramen.  Where 
the  response  to  the  test  is  negative,  the  operator  should 
look  elsewhere  in  his  radiograph  to  locate  the  mental 
foramen.  It  is  sometimes  best  to  make  an  extraoral 
radiograiDh  for  this  purpose.  Where  the  result  of  the 
electric  test  is  definitely  positive  all  doul^t  is  immediately 
and  completely  removed. 

10.  To  Differentiate  Between  the  Anterior  Palatine,  or 

Incisive,  Foramen  and  an  Abscess  Cavity 

As  with  the  mental  foramen,  the  fact  tluit  the  palatine 
foramen  may  be  mistaken  for  an  abscess  is  becoming  so 
well  known  that  there  is  danger  of  abscesses  beine:  mis- 


102  ELECTRO-RADIOGRAPHIC    DIAGNOSIS 

taken  for  the  anterior  palatine  foramen.  And,  as  in  the 
case  of  the  mental  foramen  the  electric  test,  Avlien  posi- 
tive, enables  the  operator  to  make  a  prompt  and  accurate 
diagnosis. 

When  the  test  is  negative  an  intraoral  radiograph  may 
be  made  in  such  manner  as  to  cast  the  shadow  of  the 
palatine  foramen  between  the  roots  of  the  central  in- 
cisors, instead  of  the  apex  of  the  root  of  one  of  them. 

I  have  mentioned  it  before  but  it  is  of  sufficient  im- 
portance to  justify  repetition :  When  a  radiolucent  area 
can  he  cast  aivay  from  the  end  of  the  root,  it  is  not  an 
abscess  involving  the  end  of  the  root. 

11.  To  Differentiate  between  the  Antrum  of  Highmore 
and  an  Abscess  Cavity 

One  familiar  v/itli  the  appearance  of  intraoral  dental 
radiographs  does  not  often  have  a  great  deal  of  difficulty 
in  distinguishing  the  difference  between  the  antrum  of 
Highmore  and  an  abscess  cavity,  but  one  less  skilled  in 
interpretation  often  has  a  great  deal  of  difficulty  in  this 
respect.  And  even  one  skilled  in  interpretation  will  feel 
much  more  secure  in  the  accuracy  of  his  opinion  if  he 
verifies  it  by  applying  the  electric  test  and  finds  that  the 
pulps  of  the  bicuspids  and  molars  are  vital. 

Some  points  of  difference  between  the  radiographic 
appearance  of  the  antrum  of  Highmore  and  an  abscess 
cavity  are:  Of  course  abscess  cavities  are  usually  not 
nearly  so  big  as  the  antrum,  but  a  small  antrum  may  be 
much  smaller  than  a  very  large  abscess.  The  outline  of 
the  antrum  is  more  symmetrical,  less  jagged,  than  the  out- 
line of  an  abscess  cavity,  as  a  rule.  Also  the  outline  of  the 
antrum  is  rimmed  Avith  a  thin  radiopaque  line,  represent- 
ing the  walls  of  the  antrum. 


CLINICAL   VALUE    OF    THE    TEST  103 

12.  To  Differentiate  between  the  Somewhat  Radiolucent 

Area  Which  Sometimes  Appears  in  the  Apical 

Regfion  of  Upper  Lateral  Incisors,  Due  to 

the  Canine,  or  Incisal  Fossae,  and  Radio- 

lucence  Caused  by  Infection  and 

Patholo^c  Bone  Change 

This  seems  to  the  writer  to  require  no  special  explana- 
tion. As  always  the  value  of  the  electric  test  hinges 
on  the  fact  that  a  tooth  with  a  vital  pulp  cannot  he  ab- 
scessed. 

13.  To  Differentiate  Between  Nostril  Spots  and  Abscesses 

Like  other  things  which  cause  radiolucent  areas  at  the 
apices  of  the  roots  of  teeth  without  actual  involvement  of 
the  ends  of  the  roots  of  the  teeth,  a  nostril  spot  may  be 
cast  away  from  the  end  of  the  root  by  changing  the  angle 
of  the  x-rays. 

14.  To  Aid  in  the  Recog-nition  of  Nasal  Fossse  Spots 

as  Such 

Nasal  fossEe  spots  are  so  characteristic  in  appearance 
that  it  is  only  occasionally  tliat  one  is  found  which  really 
resembles  an  abscess  cavity.  Dr.  Noboru  Teruuchi  points 
out  the  fact  that  bilateral  abscesses  of  similar  size  and 
shape,  arising  from  the  apices  of  the  roots  of  the  laterals, 
or  centrals,  might  be  mistaken  for  nasal  fossse  spots. 

15.  To  Aid  in  the  Recognition  of  the  Inferior  Dental 

Canal  as  Such 

The  inferior  dental  canal  is  characteristic  in  appear- 
ance to  the  operator  familiar  with  radiographs,  but  may 
be  mistaken  for  a  pathologic  lesion  by  one  less  familiar 
with  the  apiDearance  of  dental  radiographs.  A  positive 
reaction  from  the  application  of  the  electric  test  would 
relieve  uncertainty  in  some  cases. 


104  ELECTRO-EADIOGEAPHIC    DIAGNOSIS 

16.   To  Differentiate  Between  a  Very  Small  Abscess 
Cavity  and  an  Unusually  Large  Periapical  Space 

By  periapical  space  the  writer  does  not  mean  either  an 
air  space  or  a  vacnnm,  but  a  space  between  the  root  end 
and  the  bone;  a  space  doubtless  filled  with  vascular  tissue. 

In  the  past  there  has  been  some  discussion  as  to 
whether  such  spaces  exist.  I  have  seen  them,  and  they 
resemble  a  small  abscess  cavity.  One  cannot  confuse  a 
large  periapical  space  with  a  small  abscess  if  the  electric 
test  is  applied  and  the  pulp  found  vital. 

As  further  aids  in  differential  diagnosis  I  may  say  that 
osteosclerosis  is  likely  to  occur  in  case  of  the  abscess  and 
that  the  lamina  dura  can  probably  be  seen  unbroken  in 
the  case  of  the  large  periapical  space. 

17.  To  Differentiate  Between  a  Cancellous  Spot  of  Un- 

usual Appearance  and  an  Abscess  Cavity 

In  some  cases  the  cancellous  openings  in  the  bone  are 
abnormally  large  and  I  have  seen  them  mistaken  for  ab- 
scesses. Such  a  mistake  could  not  occur  if  the  electric 
test  were  applied  and  the  pulps  of  the  suspected  teeth 
found  vital. 

18.  To  Assist  in  Differentiation  Between  Pathologic  Con- 

ditions and  Physiologic  Conditions  about  the 
Buccal  Roots  of  Upper  Molars 

When  the  parts  are  in  a  state  of  perfect  health  there 
are  nevertheless  sometimes  radiolucent  areas  at  the  apices 
of  the  buccal  roots  of  the  upper  molars.  Also  the  disto- 
buccal  root  of  the  uioper  molar  is  so  small  that  it  some- 
times fails  to  show  clearly  in  radiographs  and  leads  the 
uninitiated  to  believe  that  there  is  root  absorption.  When 
the  fact  that  the  pulp  in  the  tooth  is  vital  can  be  estab- 
lished by  the  application  of  the  electric  test  uncertainty  in 
x-ray  interpretation  can  be  eliminated. 


CLINICAL   VALUE    OF    THE    TEST  105 

19.  To  Assist  in  Differentiation  between  Absorbed, 
Roughened  Root  and  a  Radiograph  Made  with 

the  Rays  Directed  through  the  Tooth  Diag- 
onally from  Facial  to  Lingual 

When  a  radiograph  of  the  upper  bicuspids  is  made  with 
the  rays  passing  diagonally  through  the  teeth,  the  roots 
of  the  teeth  in  the  radiograph  not  infrequently  have  a 
fuzzy,  indistinct  appearance.  I  have  seen  this  appear- 
ance of  the  root  mistaken  for  absorption  of  the  root. 
Since  the  roots  of  vital  teeth  do  not  absorb,  except  in  the 
most  extraordinary  cases,  or  in  cases  of  pressure  from  un- 
erupted  tooth  bodies,  the  establishment  of  the  fact  that 
the  pulps  are  vital  by  means  of  the  electric  test  elimi- 
nates all  except  the  remotest  possibility  of  root  absorp- 
tion. 

In  the  case  of  the  upper  bicuspids  the  small  roots  some- 
times fail  to  show  distinctly  and  so  may  seem  to  be  ab- 
sorbed, like  the  distobuccal  roots  of  upper  molars. 

20.  To  Differentiate  between  Partially  Formed  Root 

and  an  Abscess 

If  the  fact  that  the  pulp  is  vital  can  be  established  by 
means  of  the  electric  test,  this  mistake  cannot  occur.  It 
is  less  likely  to  occur  with  the  dentist  who  will  take  into 
account  the  age  of  the  patient. 

21.  To  Determine  How  Many  Teeth  Are  Involved  in  an 

Abscess 

The  writer  recalls  the  first  very  large  abscess  he  en- 
countered in  which  five  teeth  were  involved.  By  check- 
ing up  the  x-ray  findings  with  the  electric  test  and  find- 
ing that  those  teeth  Avhicli  seemed  to  be  abscessed  did 
not  respond  to  the  electric  test  I  felt  much  more  certain 
of  my  diagnosis  than  I  could  have  otherwise. 


106  ELECTEO-RADIOGRAPHIC    DIAGNOSIS 

22.  To  Assist  in  Differentiation  between  Dentoalveolar 
Abscess  and  Peridontoclasia  (Pyorrhea) 

When  serumal  calculus  on  the  roots  of  a  tooth  causes 
irritation,  which  in  turn  produces  inflammation,  and 
which  in  its  turn  results  in  suppuration,  and  the  pus  hap- 
pens to  penetrate  the  external  alveolar  plate,  instead  of 
following  along  the  side  of  the  root  and  discharging  at 
the  neck  of  the  tooth,  the  clinical  picture  is  almost  identi- 
cal with  that  of  an  ahscess.  But  if  the  electric  test  shows 
that  the  tooth  under  suspicion  of  being  abscessed  has  a 
vital  pulp  then  the  seat  of  the  suppurative  process  may 
be  looked  for  along  the  side  of  the  root  instead  of  at  the 
apex. 


THE  TEST  AS  AN  AID  IN  THE  INTERPEETATION 
OF  RADIOGRAPHS 


CHAPTER  XI 

THE  TEST  AS  AN  AID  IN  THE  INTERPRETATION 
OF  RADIOGRAPHS 

The  style  of  presenting  the  evidence  set  forth  in  this 
chapter  is  not  formal,  but,  I  hope,  it  is  convenient  and 
practical.  The  cases  illustrated  are  arranged  somewhat 
in  the  order  of  the  classes  of  cases  enumerated  in  Chap- 
ter X. 

Due  allowances  must  be  made  for  the  loss  of  detail  in 
halftones  as  compared  to  original  negatives. 

Where  definite  statements  are  made  regarding  findings 
it  is  to  be  understood  that  subsequent  treatment  and  his- 
tory verified  the  diagnoses. 

I  shall,  throughout  this  chapter,  occasionally  use  an 
illustration  which  I  cannot  interpret.  The  reason  I  can- 
not make  an  interpretation  is  that  I  do  not  have  electric 
tests  to  guide  me  and  the  reason  for  using  the  illustration 
without  giving  a  diagnosis  of  the  case  is  to  show  the 
reader  how  heavily  I  lean  on  electric  pulp  test  findings. 

Fig.  43.  Failure  of  the  lower  first  bicuspid  to  respond 
normally  to  the  electric  test  directed  attention  to  the 
tooth.  The  radiograph  shows  evidence  of  a  large  abscess 
cavity.  There  were  no  local  symptoms  or  signs  at  all. 
Had  the  electric  test  not  been  used  a  radiograph  would 
not  have  been  made  of  this  tooth  and  the  area  of  infection 
would  not  have  been  found.  On  the  enamel  of  the  lower 
first  bicuspid  the  electric  test  was  definitely  negative.  On 
the  metal  of  the  occlusal  filling  it  was  very  faintly  posi- 
tive. Normally  it  should  have  been  positive  (+)  on  enamel 
and  positive  very  strong  (+VS)  on  the  metal  filling. 
Hence  I  have  said  that  the  tooth  did  not  respond  nor- 
mally to  the  test,  even  though  a  faint  positive  was  ob- 
tained on  the  simple  occlusal  filling. 

108 


INTERPRETATION    OF    RADIOGRAPHS 


109 


Fig.   43. 


Fig.   44. 

Fig.  44.  If  one  were  making  a  casual  examination  of 
the  mouth  to  determine  which  teeth  were  ''suspicious" 
and  should  therefore  be  radiographed,  it  is  unlikely  that 
the  little  filling  in  the  upper  lateral  incisor  would  arouse 
suspicion  of  a  dead  pulp.  But  when  the  electric  test  is 
used  and  the  lateral  fails  to  respond,  suspicion  is  aroused. 
The  radiograph  shows  the  lateral  incisor  abscessed. 


110  ELECTRO-EADIOGRAPHIC    DIAGNOSIS 


Fig.  45.  Tlie  abcessed  lower  lateral  was  located  by 
means  of  tlie  electric  test.  The  symptoms  were  sucli — 
there  was  a  fistula — that  it  Avas  known  that  one  or  more 
of  the  six  anterior  teeth  w^ere  abscessed.  Just  which  one 
was  determined  by  the  use  of  the  electric  test.  The  test 
finding  was  verified  by  the  radiograph.  Also  the  radio- 
graph shows  the  extent  of  the  loss  of  osseous  tissue.  In 
the  absence  of  an  x-ray  machine  the  offending  tooth 
would  have  been  located  by  the  test  unaided  by  radio- 
graphs.   No  cavity  in  the  abscessed  tooth. 

Fig.  46.  History  of  this  case  when  it  presented  was 
that  "an  abscessed  lower  lateral  incisor  has  been  ex- 
tracted a  month  previously.  Pus  still  discharging  from 
the  socket  of  the  extracted  tooth. ' '  The  electric  test  was 
applied  to  the  central  incisor  and  cuspid  approximating 
the  socket  of  the  extracted  tooth.  The  central  incisor 
responded  positive  (+)  the  cuspid  negative  (-).  Thus  a 
diagnosis  was  made  readily  enough  before  the  radiograph 
was  made.  The  radiograph  verifies  the  diagnosis,  show- 
ing the  fistulous  tract  of  the  abscess  arising  at  the  apex 
of  the  cuspid  and  passing  over  into  the  socket  of  the  ex- 
tracted lateral  incisor. 


INTERPRETATION"    OF    RADIOGRAPHS 


111 


Fig.  4S. 


Fig.  46. 


112  ELECTRO-RADIOGRAPHIG    DIAGNOSIS 


Fig.  47.  Three  blind  abscesses  at  the  apices  of  the  up- 
per incisors.  The  fact  that  the  pulps  were  dead  in  these 
teeth  could  have  been  established  by  the  use  of  the  electric 
test.  The  radiograph  was  necessary  to  show  the  amount 
of  bone  destruction.  The  teeth  have  artificial  enamel  fill- 
ings in  them.  I  am  told  that  the  first  silicious  cements 
placed  on  the  market  contained  some  ingredient  which 
devitalized  pulps.  I  cannot  vouch  for  the  truth  of  this. 
Absolutely  all  I  know  about  the  matter  is  this:  I  have 
found  a  sufficient  number  of  dead  pulps  in  teeth,  with  ar- 
tificial enamel  in  them,  so  that  I  am  particularly  careful 
to  test  such  teeth  for  pulp  vitality.  More  of  this  material 
is  being  used  alll;he  time  but  I  do  not  notice  any  increase 
in  pulp  death  in  teeth  filled  with  it  which  would  seem  to 
indicate  that  the  silicious  cements  now  in  use  do  not  con- 
tain a  pulp  devitalizing  ingredient.  (Radiograph  by  Al- 
ger of  Los  Angeles.) 

Figs.  48  and  49.  These  two  radiographs  illustrate  the 
necessity  of  checking  up  x-ray  findings.  In  Fig.  48  the 
abscess  arising  from  the  lower  cusj)id  seems  to  involve 
the  adjoining  lateral  incisor  and  perhaps  the  central  in- 
cisor also.  But  the  electric  test  for  pulp  vitality  indi- 
cates that  the  pulps  in  the  incisors  are  vital  and  there- 
fore not  involved  in  the  abscess. 

In  Fig.  49  the  central  incisor  looks  as  though  it  might 
be  involved  in  the  abscess  of  the  lateral  incisor  though  its 
appearance  is  no  more  suspicious  than  the  lower  incisors, 
particularly  the  lateral,  in  Fig.  48.  The  fact  that  the 
upper  central  is  negative  to  the  electric  test  while  the 
lower  incisors  are  positive,  is  what  tells  us  that  the  upper 
incisor  is  abscessed  and  that  the  lower  incisors  are  not. 


INTERPRETATION    OF    RADIOGRAPHS 


Fiff.   47. 


Fig.  48. 


Fig.  49. 


114  ELECTRO-RADIOGEAPHIC    DIAGNOSIS 


Figs.  50  and  51.  Fig,  50  is  a  postoperative  radiograph 
made  following  the  root  resection  of  the  upper  first  bi- 
cuspid. The  film  just  takes  in  the  apex  of  the  lateral  in- 
cisor. It  looked  "suspicions"  and  was  tested.  Result 
negative  (-).  Another  radiograph  (Fig.  51)  was  made. 
The  slight  area  of  osteoclasia  can  be  seen  quite  clearly. 
The  pulp  of  the  lateral  was  dead  and  the  tooth  abscessed. 

Fig.  52.  In  this  radiograph  the  upper  third  molar  is 
missing  and  the  shadow  of  the  malar  bone  falls  over  the 
first  molar,  the  one  on  the  reader's  left.  There  is  a  very 
suspicious  radiolucent  area  above  the  apex  of  the  second 
molar.  But  the  second  molar  responds  so  perfectly  to  the 
electric  test  that  we  are  safe  in  saying  that  the  pulp  is 
vital  and  that  the  radiolucent  area  is  not  an  abscess. 

Fig.  53.  We  have  seen  the  necessity  of  checking  up 
x-ray  findings  with  the  electric  test.  Now  let  me  illus- 
trate the  necessity  of  checking  up  pulp  test  findings  with 
radiographs.  The  u|)per  cuspid  was  quite  definitely  nega- 
tive to  the  strongest  current.  The  radiograph  shows  the 
reason  for  it;  the  pulp  has  receded  away  above  the  gum 
line.  The  pulp  is  vital  but  the  current  could  not  pene- 
trate the  secondary  dentin  to  the  pulp. 

Fig.  54.  The  lower  cuspid  responded  positive  but  very 
weak  (+VA¥).  The  reason  it  responds  so  weakly  to  the 
electric  test  is  seen  in  the  radiograph,  i.e.,  the  large  pulp 
stone.  The  first  molar  is  abscessed.  Considerable  peri- 
dontoclasia  about  the  cuspid. 


INTERPRETATION    OF    RADIOGRAPHS 


115 


Fig.   50. 


Fig.  51. 


Fig.  52. 


Fig.   53 


Fig.   54. 


116  ELECTRO-EADIOGEAPHIC    DIAGjSTOSIS 


Fig.  55.  This  radiograpli  illustrates  the  expediency  of 
the  rule  to  test  the  teeth  on  either  side  of  the  one  sus- 
pected of  being  abscessed.  A  fistula  pointed  just  to  the 
distal  of  the  apex  of  the  root  of  the  second  bicuspid  and 
so  it  was  susjDected  of  being  an  abscessed  tooth.  The 
radiograpli  shows  a  definite  radiolucent  area  just  to  the 
distal  of  the  apex  of  the  second  bicuspid,  and  involving 
its  apex. 

But  the  results  of  the  application  of  the  test  were  as 
follows:  Second  bicusj)id  joositiye  (+),  first  molar  positive 
(+),  first  bicuspid  negative  (-).  A  close  study  of  the 
radiograph  with  the  tests  as  a  guide  resulted  in  observa- 
tion of  a  fistulous  tract  leading  from  the  first  bicuspid  to 
the  radiolucent  spot  in  the  apical  region  of  the  second  bi- 
cuspid.   (Radiograph  by  Alger  of  Los  Angeles.) 

Figs.  56,  57,  and  58.  Figs.  56  and  57  were  made  at  the 
same  sitting.  They  show  the  apex  and  periapical  tissues 
of  the  upper  lateral  incisor  at  Avidely  different  angles. 
Neither  of  them  show  any  bone  change  which  might  be 
taken  as  evidence  of  a  septic  pulp  in  the  lateral.  The 
lateral  did  not  resj^ond  to  the  electric  test  for  pulp  vitality 
though,  and  the  operator  who  referred  the  case  was  ad- 
vised to  make  a  diagnostic  opening  into  the  lateral  in- 
cisor. The  ojDerator  pinned  his  faith  in  the  aj)pearance 
of  radiographs  and  did  not  make  a  diagnostic  opening. 

Fig.  58  was  made  seven  months  later.  We  now  see 
quite  definite  bone  destruction  above  the  aj^ex  of  the 
lateral  incisor. 


liSTTEEPRETATIOX    OF    RADIOGRAPHS 


117 


Fig.   55. 


Fig.   56. 


Fig.  57. 


Fig.  58. 


118  ELECTRO-RADIOGEAPHIC    DIAGlirOSIS 


Figs.  59,  60,  and  61.  These  three  illustrations  have 
been  made  experimentally  from  a  skull.  Fig.  59  does  not 
show  the  apical  bone  destruction,  while  Figs.  60  and  61, 
made  at  different  angles,  do.  Suppose  we  should  have  a 
radiograph  of  a  tooth  like  the  second  bicuspid  in  Fig.  59. 
There  would  be  nothing  in  such  a  radiograph  to  warn  us 
sufficiently  of  the  necessity  of  making  the  radiograph 
over  at  different  angles,  unless  we  had  records  of  the  ap- 
plication of  the  electric  test. 

Fig.  62.  Another  view  of  the  parts  in  which  the  angle 
at  which  exposure  was  made  was  correct.  No  distortion 
of  the  image  and  the  abscess  shows. 

Figs.  63  and  64.  When  Ave  have  reason  to  believe  a 
tooth  is  pulpless,  or  we  know  it  as  we  do  in  the  case 
of  the  shell  crowned  upper  molar  because  we  can  see  some 
canal  filling,  then  we  are  fully  aware  of  the  necessity  of 
getting  a  good  radiographic  view  of  the  tooth.  But  if  we 
have  no  idea  whether  the  pulp  is  vital  or  not  then  we  do 
not  know  exactly  how  thorough  our  radiographic  exam- 
ination should  be.  Fig.  63  fails  to  show  the  abscess 
of  the  upper  molar,  while  Fig.  64,  the  last  one  made, 
shows  it,  or,  to  be  meticulous,  it  shows  a  radiolucent  area 
which  I  take  to  be  an  abscess  cavity.  It  is  not  infre- 
quently necessary  to  deliberately  distort  upper  molars  in 
order  to  cast  the  shadow  of  the  mesiobuccal  or  disto- 
buccal  roots  far  enough  mesially  or  distally  to  observe 
the  tissues  at  their  apices. 


INTERPRETATION    OF    RADIOGRAPHS 


119 


Fig.   59. 


Fig.  60. 


Fig.  61. 


Fig.  62. 


Fig.  63. 


Fig.   64. 


120  ELECTRO-EADIOGEAPHIC    DIAGNOSIS 


Fig.  65.  Pericementitis  of  the  second  molar.  Tootli 
carries  very  large  amalgam  filling.  Electric  test  positive 
weak  (+W).  Tootli  more  tender  to  pressure  to  the  distal 
than  to  mesial  or  mesio-vertical  pressure.  The  radio- 
graph shows  the  reason  for  the  pericementitis.  The  filling 
in  the  distal  of  the  second  molar  and  the  filling  in  the 
mesial  of  the  third  molar  both  hang  into  the  interproxi- 
mal space  causing  irritation,  inflammation,  and  osteo- 
clasia. 

Fig.  66.  The  radiolucent  spots  at  the  apices  of  the 
cuspid  and  the  second  bicuspid  are  of  about  the  same  size 
and  almost  the  same  general  appearance.  The  spot  at  the 
apex  of  the  second  bicuspid  I  believe  to  be  osteoclasia 
and  odontoclasia,  due  to  infection,  in  short  a  spot  due  to 
a  pathologic  process,  while  the  spot  at  the  apex  of  the 
cuspid  is  plw siologic ;  that  is  to  say,  it  does  not  represent 
disease.  The  fact  that  the  cuspid  responds  positively  (+) 
to  the  electric  test  is  very  strong,  I  might  almost  say  con- 
clusive, evidence  of  the  correctness  of  the  opinion  regard- 
ing the  cuspid. 

Also  there  is  a  small  "suspicious  spot"  in  the  apical 
region  of  the  first  bicuspid,  but  the  tooth  responds  posi- 
tively (+)  to  the  electric  test  and  so  I  do  not  look  upon 
this  area  as  a  spot  of  infection. 

Fig.  67.  The  small  radiolucent  spot  at  the  apex  of  the 
root  of  the  second  bicuspid  might  be  looked  upon  as  evi- 
dence of  infection  if  it  were  not  for  the  fact  that  this 
tooth  has  a  vital  pulp,  Avhieh  fact  has  been  established  by 
its  very  definitely  positive  (+S)  response  to  the  electric 
test  for  pulp  vitality.  A  gold  shell  crown  has  been  re- 
moved to  test  this  tooth,  a  procedure  which  is  not  infre- 
quently indicated. 


INTERPRETATION    OF    RADIOGRAPHS 


121 


*^B| 

lA 

iM 

[1 

Fig.  65. 


Fig.   66. 


Fig.  67. 


122  ELECTRO-KADIOGRAPHIC    DIAGNOSIS 


Fig.  68.  I  do  not  have  pulp  testing  records  of  this  case. 
Therefore  I  cannot  say  whether  the  small  radiolucent 
areas  at  the  apices  of  the  lower  central  incisors  repre- 
sent areas  of  infection  or  not.  The  fact  that  one  of  them 
seems  to  be  broken  off  is  contributory  evidence  of  abscess. 
Bnt,  I  would  not  wish  to  give  a  final  opinion  without  re- 
course to  the  electric  test  for  pulp  vitality. 

Figs.  69  and  70.  These  two  radiographs  are  of  the 
same  case.  They  are  reproduced  here  (by  courtesy  of  the 
publishers  of  my  book  "Elementary  and  Dental  Radi- 
ography") because  it  was  this  case  which  first  impressed 
me  wdtli  the  extreme  value  of  the  electric  test,  and  caused 
me  to  have  test  record  sheets  printed  and  make  it  routine 
practice  to  apply  the  test  in  practically  all  radiodontic 
cases. 

The  following  history  of  the  case  is  quoted  from  "Ele- 
mentary and  Dental  Radiography": 

"The  end  of  the  root  of  an  upper  lateral  was  resected 
to  cure  an  abscess.  The  wound  made  at  the  time  of  opera- 
tion did  not  heal  normally,  A  radiograph  was  made  (Fig. 
69) .  It  seems  to  show  that  the  central  is  involved  in  the 
lateral's  abscess  cavity.  The  central  was  tested  for  vital- 
ity of  its  pulp.  It  responded  to  the  electric  test,  indicat- 
ing a  vital  pulp.  Another  radiograph  was  made,  Fig.  70. 
This  second  radiograph,  made  at  a  different  angle,  shows 
no  involvement  of  the  central,  and  what  may  or  may  not 
be  an  involvement  of  the  cuspid.  The  shadow  passing  to 
the  apex  of  the  cuspid  does  not  show  clearly.  The  cuspid 
was  tested  and  its  pulp  did  not  respond  to  the  application 
of  the  current.  It  was  opened  and  found  to  contain  a 
putrescent  pulp.  Neither  the  central  incisor,  at  first 
suspected,  nor  the  cuspid,  finally  opened,  had  carious  cav- 
ities in  their  crowns. 


INTERPRETATION    OF    RADIOGRAPHS 


123 


Fig.  68. 


Fig.  69. 


^■^^  ^^         ^^^i^^^^B 

I            .  ^  '■  ^^        1 

Fig.  70. 


124  ELECTRO-RADIOGRAPHIC   DIAGNOSIS 

Figs.  71  and  72.  I  do  not  have  the  electric  test  records 
for  this  case  and  I  cannot  therefore  give  a  reliable  inter- 
pretation of  the  radiographs.  I  see  by  Fig.  72  that  the 
central  incisor  has  been  opened,  but  whether  the  operator 
found  a  vital  or  a  septic  pulp  I  cannot  tell  from  the  radio- 
graph. My  guess  from  observation  of  Fig.  71  is  that  the 
cuspid  harbors  a  vital  pulp,  but  I  would  not  want  to  give 
a  final  opinion  without  the  electric  test  to  help  me.  (Ra- 
diographs by  McCormick.) 

Fig.  73.  The  radiolucent  area  at  the  apex  of  the  cuspid 
gives  the  tooth  the  appearance  of  being  abscessed,  but  it 
is  not.  It  responds  positively  to  the  electric  test.  The 
abscess  arises  from  the  lingual  root  of  the  first  bicuspid, 
the  crowned  tooth. 

Fig.  74.  The  appearance  of  this  radiograph  is  such  as 
to  direct  suspicion  to  the  lateral  incisor  and  cuspid.  There 
is  considerable  bone  destruction  between  these  two  teeth, 
and  the  area  of  radiolucence  extends  slightly  beyond  the 
apex  of  the  lateral  incisor.  But  both  of  these  teeth — the 
lateral  and  cuspid — respond  positively  (+)  to  the  electric 
test;  so  does  the  central  incisor.  But  the  first  bicuspid 
responds  negatively  (-).  The  pulp  in  the  first  bicuspid 
was  found  devitalized  and  septic.  The  abscess — i.e., 
source  of  bone  destruction — was  from  the  lingual  root  of 
the  first  bicuspid. 

Figs.  75  and  76.  Different  views  of  the  same  case. 
Both  the  lateral  incisor  and  the  first  bicuspid  are  involved 
in  a  very  large  abscess.  And,  certainly,  the  cuspid  has 
the  radiographic  appearance  of  being  involved  also — but 
it  is  not.  It  responded  (+)  to  the  electric  test.  Subse- 
quent history  proved  correctness  of  diagnosis. 

It  will  probably  not  show  in  the  halftone,  but,  in  the 
negative,  a  radiolucent  line  (the  usual  line  indicating  the 
pericemental  membrane)  could  be  seen  following  the  cus- 
pid root.     The  presence  of  this  line  could  not  be  con- 


INTEKPRETATION    OF    EADIOGKAPHS 


125 


Fis.  71. 


Fig.  73. 


Fig.  74. 


Fig.  75. 


Fig.  "i^i. 


126  ELECTRO-EADIOGEAPHIC    DIAGiSTOSIS 

sidered  proof  of  the  vitality  of  tlie  tooth,  but  it  was  con- 
tributory evidence  of  vitality.  Not  even  the  presence  of 
both  the  radiolncent  line,  indicating  the  pericemental 
membrane,  and  the  radiopaque  line,  indicating  the  lamina 
dura  (i.e.,  the  dense  layer  of  bone  lining  tooth  sockets) 
proves  the  pulp  of  the  tooth  vital  and  the  tooth  not  ab- 
scessed.   (See  Fig.  59.) 

Fig.  77.  The  radiographic  appearance  of  the  lateral 
incisor  in  this  illustration  is  quite  similar  to  that  of  the 
cuspid  in  Figs.  75  and  76.  Yet,  in  this  case,  the  lateral 
is  involved  in  the  abscess,  while  the  cuspid,  in  Figs.  75 
and  76,  is  not.  It  is  the  electric  test  for  jDulp  vitality  that 
gives  us  the  information  necessary  to  the  correct  inter- 
pretation of  the  radiographs  in  these  cases. 

Fig.  78.  This  illustration  is  similar  in  appearance  to 
Figs.  75  and  76.  I  regret  that  I  cannot  locate  my  records 
for  this  case.  My  recollection  is  that  the  cuspid  re- 
sponded positive  (+)  to  the  test  and  was  not  involved  in 
the  large  abscess. 

Figs.  79,  80,  81,  and  82.  Showing  variation  in  the  loca- 
tion of  the  mental  foramen. 

Fig.  79.  The  mental  foramen  considerably  below  the 
apices  of  the  roots  and  midway  between  the  first  and  sec- 
ond bicuspid. 

Fig.  80.  The  mental  foramen  above  the  apices  of  the 
roots  just  to  the  mesial  of  the  second  bicuspid. 

Fig.  81.  The  mental  foramen  at  the  apex  of  the  root  of 
the  second  bicuspid.  Similar  in  appearance  to  an  abscess 
area,  but  a  positive  (+)  reaction  to  the  electric  test  elimi- 
nates the  possibility  of  abscess. 

Fig.  82.  The  mental  foramen  at  the  apex  of  the  first 
bicuspid.  This  is  a  little  farther  forward  than  one  ordina- 
rily finds  the  foramen  and  so  the  test  is  particularly 
needed  to  make  sure  that  the  pulp  in  the  first  bicuspid  is 
vital. 


INTERPRETATIO:?^    OF    RADIOGRAPHS 


12- 


Fig.   77. 


Fig.   78. 


Fig.  79. 


Fig.  81. 


Fig.  82. 


128  ELECTRO-RADIOGEAPHIC    DIAGNOSIS 


Fig.  83.  When  in  doubt,  it  is  sometimes  expedient  to 
make  an  extraoral  radiograph  to  assist  in  differentiation 
between  an  abscess  and  the  mental  foramen.  If  a  spot  is 
seen  at  the  apex  of  one  of  the  bicuspid  teeth  and  the  men- 
tal foramen  can  be  seen  elsewhere,  then  the  spot  at  the 
apex  of  the  tooth  must  be  an  abscess — or  a  large  cancel- 
lous spot  in  the  bone.  And  one  can  get  a  fair  idea  as  to 
whether  it  is  a  large  cancellous  spot  or  not,  by  the  general 
appearance  of  the  bone,  a  considerable  area  of  which  can 
be  seen  in  an  extraoral  radiograph.  In  this  illustration 
the  mental  foramen  is  at  the  apex  of  the  second  bicuspid. 


IISTTERPRETATION    OF    RADIOGRAPHS 


129 


Fig.  83. 


130  ELECTRO-EADIOGKAPHIC    DIAGNOSIS 


Fig.  8-t.  Abscess  at  apex  of  first  bicuspid.  Opinion 
verified  by  fact  that  tooth  tests  negative  (-) . 

Fig.  85.  Abscessed  lower  bicuspid.  The  radiolucent 
area  might  easily  have  been  mistaken  for  the  mental  fora- 
men, particularly  because  the  tooth  has  no  carious  cavity 
in  it.  Its  response  to  the  electric  test  was  negative,  how- 
ever, which  led  to  the  correct  interpretation  of  the  radio- 
graph. 

Fig.  86.  That  the  radiolucent  area  at  the  apex  of  the 
second  bicuspid  is  of  pathologic  origin,  and  not  the  mental 
foramen,  is  indicated  rather  conclusively  b^^  the  fact  that 
the  tooth  resjDonds  negative  (-)  to  the  electric  test.  The 
radiolucent  area  in  this  case  has  more  the  appearance  of 
an  abscess;  it  is  too  large  for  a  normal  mental  foramen. 
The  tooth  has  no  cavitv  in  it. 


INTERPRETATION    OF    RADIOGRAPHS  131 


Fig.  84. 


Fig.  85. 


Fig.   86. 


132  ELECTRO-EADIOGRAPHIC    DIAGNOSIS 

Fig.  87.  A  photograph  of  a  skull  showing  the  anterior 
palatine  foramen,  also  called  the  incisive  foramen. 

Fig.  88.  The  large  radiolncent  area  and  the  short  root 
of  the  central  incisor  would  lead  the  unwary  and  the  non- 
user  of  the  electric  test  to  suspect  that  we  have  here  a 
dentoalveolar  abscess  exhibiting  considerable  tissue  de- 
struction both  osseous  and  dental.  The  facts  are  that  the 
radiolncent  area  is  the  anterior  palatine  foramen  and  the 
root  of  the  tooth  is  malformed  and  short,  not  absorbed. 

The  radiograph  is  of  the  dry  specimen  shown  in  Fig. 
87,  in  which  the  shadow  of  the  anterior  palatine  foramen 
has  deliberately  been  cast  at  the  apex  of  one  of  the  central 
incisors  giving  it  (the  foramen)  the  appearance  of  an  ab- 
scess area.  In  order  to  cast  the  shadow  of  the  foramen  at 
the  apex  of  the  central  incisor  tooth,  the  horizontal  angle 
of  the  x-ray  was  somewhat  as  indicated  in  Fig.  87  by  ar- 
row No  1. 

Fig.  89.  Another  radiograph  of  Fig.  87,  which  like 
Fig.  88,  shows  the  anterior  palatine  foramen  at  the  apex 
of  the  central  incisor. 

Figs.  90  and  91.  Two  radiographs  made  at  different 
angles  from  Figs.  88  and  89,  in  Avhich  the  shadow  of  the 
anterior  palatine  foramen  is  cast  between  the  roots  of 
the  central  incisors  instead  of  at  the  apex  of  one  of  them. 
The  horizontal  angle  to  make  these  radiographs  was  more 
like  No.  2  than  arrow  No.  1  of  Fig.  87. 

The  combination  of  central  and  lateral  incisors  on  one 
intraoral  radiograph  is  a  good  combination  to  get  a  good 
view  of  the  parts,  but  the  operator  should  be  rather  care- 
ful to  have  his  horizontal  angle  as  indicated  by  arrow  No. 
2  and  not  as  indicated  by  arrow  No.  1  else  the  anterior 
palatine  foramen  may  be  mistaken  for  an  abscess.  This  is 
especially  true  when  the  central  incisors  are  known  to  be 
pulpless. 


INTEEPEETATION    OF    RADIOGRAPHS 


13- 


Fig.  87. 


Fig.  88. 


Fig.  89. 


Fig.  90. 


Fig.  91. 


134  ELECTRO-EADIOGRAPHIC    DIAGNOSIS 


Figs.  92  and  93.  In  Fig.  92  a  radiolucent  area  is  seen 
at  the  apex  of  the  central  incisor,  with  the  large  inlay  in 
it,  having  the  ajDpearance  of  an  abscess.  The  tooth  re- 
sponds positively  (+)  to  the  electric  test,  however,  which 
indicates  that  the  pnliD  of  the  central  is  vital  and  there- 
fore that  the  radiolucent  spot  at  its  apex  is  the  incisive 
foramen  and  not  an  abscess  cavity. 

Fig.  93  is  another  radiograph  of  the  same  case  as  Fig. 
92,  made  at  a  different  angle.  The  shadow  of  the  anterior 
palatine  foramen  is  no  longer  seen  at  the  apex  of  the 
central  incisor  with  the  large  inlay.  It  can  be  seen  faintly 
between  the  apices-  of  the  central  incisors. 

Figs.  94  and  95.  Two  radiographs  of  the  same  case 
which,  like  Figs.  92  and  93,  show  the  anterior  palatine 
foramen  at  the  apex  of  a  central  incisor  from  one  view 
(Fig.  94)  and  between  the  apices  of  the  roots  of  the  in- 
cisors from  another  view  (Fig.  95). 

Fig.  96.  A  colleague  sends  me  this  radiograph  and  as- 
sures me  that  there  are  no  symptoms  or  signs  of  cyst  and 
that  the  pulp  of  the  central  incisor  is  vital.  Accepting 
this  information  as  true,  I  should  say  we  have  here  a  very 
large  and  most  unusual-appearing  anterior  palatine  fora- 
men. 

Fig.  97.  Another  anterior  palatine  foramen  of  some- 
what unusual  appearance. 


IXTEKPRETATIOX    OF    RADIOGRAPHS 


yjLJ 


135 


Fie.  92. 


Fie.  9A 


Fig.  55. 


Fig.  96. 


Fig.  &/. 


136  ELECTKO-EADIOGPvAPHIC    DIAGNOSIS 


Figs.  98  and  99.  Dr.  Mathew  Cryer,  long  before  the 
nse  of  x-rays  became  popular,  wrote  a  genuine  master- 
piece of  a  book  entitled  ''Internal  Anatomy  of  the  Face." 
It  was  this  little  book  that  first  taught  us  of  the  tremen- 
dous variability  of  the  antrum  of  Highmore  in  size,  shape, 
and  location.  The  use  of  radiographs  have  fully  borne 
out  Dr.  Cryer's  teaching. 

Figs.  98  and  99  are  the  right  and  left  side  of  the  same 
case  and  show  a  very  large  antrum  of  Highmore.  In  cases 
such  as  this  it  is  a  relief  to  be  able  to  test  the  teeth  with 
the  electric  test  and  find  them  vital.  It  verifies  one's 
opinion.  In  this  particular  case  the  crowned  teeth  could 
not  be  tested,  but  all  the  other  teeth  were  tested  and  re- 
sponded (+).     Compare  Figs.  98  and  99  with  Fig.  126. 

Figs.  100  and  101.  Two  radiographs  of  the  same  case, 
made  at  slightly  different  angles.  Compare  the  antrum 
in  this  case  to  the  ones  shown  in  Figs.  98  and  99. 

This  one  has  very  much  the  appearance  of  an  abscess 
cavity  arising  from  the  second  bicuspid  or  first  molar. 
Both  bicuspids  and  both  molars  test  positively  (+)  how- 
ever. The  second  molar  responds  positive  strong  (+S). 
The  reason  for  it  is  the  carious  cavity  in  the  distal  sur- 
face. 

Figs.  102  and  103.  Two  cases  in  which  the  first  molars 
responded  negative  (-)  to  the  electric  test.  Both  had 
septic  pulps.  Fig.  102  shows  evidence  of  cyst  formation. 
The  radiographic  evidence  of  infection  in  these  cases 
might  easil}^  have  been  overlooked — i.e.,  mistaken  for 
antrum  shadows — ^had  it  not  been  for  the  electric  test 
which  directed  especial  attention  to  them. 


HSrTERPRETATION    OF    RADIOGRAPHS 


137 


Fig. 


Fig.  99. 


Fig.   100. 


Fig.   101. 


Fig.   102. 


Fig.   lOo 


138  ELECTRO-EADIOGEAPHIC    DIAGNOSIS 


Figs.  104  and  105.  The  two  sides  of  the  same  case 
showing  antra  of  more  or  less  typical  appearance. 

Figs.  106  and  107.  Fig.  106  exhibits  a  shadow  over  the 
cnspid  and  first  bicuspid  which  might,  from  the  radio- 
graphic ai^pearance,  be  mistaken  for  an  abscess  or  cyst. 
Both  the  first  bicuspid  and  the  cuspid  res^Dond  positive 
(+)  to  the  electric  test.  The  shadow  at  their  apices  is  the 
maxillary  sinus.  Fig.  107  is  another  case  in  which  the 
antrum  is  seen  so  far  forward  it  overlaps  (in  the  radio- 
graph) the  end  of  the  root  of  the  cuspid. 

Figs.  108  and  109.  Right  and  left  sides  of  the  same  case. 
Another  case  in  which  the  shadow  of  the  antrum  comes 
rather  far  forward.  The  radiopaque  lines  indicating  the 
walls — i.e.,  the  dense  cortical  bone — surrounding  the  an- 
trum can  be  seen  rather  clearly  in  this  case.  The  opinion 
that  the  large  radiolucent  areas  are  the  maxillary  sinuses 
is  strengthened  by  the  results  of  the  application  of  the 
electric  test.  All  teeth  test  positive  (+),  except  the  lateral 
incisors.  The  dark  area  in  the  region  of  the  left  lateral 
(Fig.  108)  is  of  infectious  origin. 


IXTEIVPItETATlOX    OF    EADIOGEAPHS 


139 


Fig.   104. 


Fig.   105. 


Fi.s;.   106. 


Fig.   107. 


Fig.  108. 


Fig.  109. 


140  ELECTRO -RADIOGRAPHIC    DIAGIiTOSIS 


Fig.  110.  This  radiograph  illustrates  a  rather  typical 
appearance  of  radiolucency  in  the  apical  region  of  the 
upper  lateral  incisor,  due  to  the  canine  or  incisal  fossae,  a 
depression  just  mesially  to  the  canine  eminence. 

In  passing,  note  the  recession  of  the  pulp — the  throw- 
ing U13  of  secondary  dentin  as  it  retreats — caused  by  the 
carious  cavity  in  the  tooth. 

Figs.  Ill  and  112.  In  this  case  the  radiolucency  in  the 
apical  region  of  the  lateral  incisor  is  too  pronounced  to  be 
considered  physiologic.  Yet  the  lateral  responds  positive 
(+)  to  the  electric  test.  So  do  the  approximating  central 
incisor  and  cuspid.  The  cause  of  the  radiolucency,  in  the 
region  of  the  apex  of  the  lateral,  which  by  the  way  can  be 
seen  extending  over  toward  the  cuspid,  arises  from  the 
badly  diseased  first  bicuspid. 

Fig.  113.  Radiolucency  in  the  apical  area  of  the  lateral 
on  the  reader's  left.  Tooth  negative  (-)  to  electric  test. 
Tooth  abscessed.  The  radiolucent  area  due  to  the  abscess 
and  the  nasal  fossa  spot  on  that  side  merge  into  one  an- 
other. 

Figs.  114  and  115.  The  f  ossa3  spots  can  usually,  but  not 
always,  be  seen  in  radiographs  of  the  upper  incisor  teeth. 
Other  things  being  equal,  the  higher  the  angle  of  the 
x-rays  at  the  time  of  exposure,  the  lower  down — i.e.,  closer 
to  the  apices  of  the  roots  of  the  upper  incisor  teeth — fall 
the  shadows  of  the  nasal  fossae. 

The  nasal  fossae  spots  in  Fig.  114  are  removed  a  con- 
siderable distance  from  the  apices  of  the  roots  of  the  in- 
cisor teeth,  while  in  Fig.  115  the  nasal  fossae  spots  are 
just  above  the  apices  of  the  incisors.  This  difference  is 
due  partly  to  differences  in  the  cases  and  partly  to  differ- 
ences in  the  angle.  Fig.  114  is  more  typical  in  appear- 
ance than  Fig.  115. 


IlSrTERPRETATION    OF    RADIOGRAPHS 


141 


Fig.  110. 


Fig.   111. 


Fig.   112. 


Fig.   113. 


Fig.  114. 


Fig.   ILS. 


142  ELECTRO-EADIOGRAPHIC    DIAGNOSIS 


Fig.  116.  Another  case  in  Avliicli  tlie  nasal  fossse  spots 
are  ratlier  low  down  and  in  wliicli  tlie  shadow  of  the  ah- 
scess  of  the  central  incisor,  on  the  reader's  left  merges 
into  the  shadow  of  the  nasal  fossae. 

Fig.  117.  The  disto-hnccal  root  of  the  npper  first  molar 
seems  to  be  absorbed  but  the  tooth  is  vital — responds 
positive  (+)  to  the  electric  test — and  very  often  the  disto- 
buccal  roots  of  npper  molars  are  not  bulky  enongli  to 
register  in  radiographs  clearl}^ 

The  spot  at  the  apex  of  the  first  bicuspid  is  of  about 
the  same  size  and  appearance  as  the  spot  at  the  apex  of 
the  second.  However,  the  first  bicuspid  responds  positive 
(+)  to  the  electric  test.  Therefore  the  spot  at  its  apex 
cannot  be  osteoclasia  due  to  infection. 

Figs.  118  and  119.  The  same  radiograph  developed  to 
different  degrees  of  intensity  in  an  effort  to  show  both  the 
roots  and  the  pulp  chamber  without  retouching,  or  at 
least  with  the  minimum  of  retouching. 

The  disto-buccal  root  of  the  first  molar  seems  to  be 
absorbed.    But  we  have  learned  this  ma,}^  be  ph^^siologic. 

How  about  this  though  ?  The  tooth  responds  hardly  at 
all  (+VAV)  to  the  electric  test! 

The  pulp  of  the  tooth  is  vital.  The  reason  it  does  not 
respond  better  to  the  electric  test  is  disclosed  by  a  study 
of  the  shape  of  the  pulp  chamber.  The  presence  of  the 
large  metal  restoration  in  the  crown  has  caused  recession 
of  the  pulp  and  development  of  secondary  dentin.  The 
distal  half  of  the  pulp  chamber  is  obliterated. 


INTERPRETATION    OF    RADIOGRAPHS 


143 


Fig.   116. 


Fig.   117. 


Fig.   118. 


Fig.   119. 


144  ELECTRO-RADIOGRAPHIC    DIAGNOSIS 


Figs.  120  and  121.  Radiograplis  of  the  same  case  made 
at  different  angles.  Fig.  120  was  made  with  the  x-rays 
passing  straight  through  the  teeth  from  facial  to  lingual. 
Fig.  121  was  made  with  the  x-rays  passing  diagonally 
through  the  teeth  from  facial  to  lingual.  Note  how  in- 
distinct the  root  outlines  are  in  Fig.  121.  I  have  seen  this 
indistinctness  of  root  outline  due  to  angle  mistaken  for 
absorption  of  the  root  due  to  disease.  The  roots  par- 
ticularly susceptible  to  this  sort  of  distortion  are  :  (1)  Up- 
per bicuspids  (2)  Lower  molars  (3)  Mesio-buccal  roots 
of  upper  molars. 

Where  the  electric  test  can  be  applied  satisfactorily  and 
a  positive  reaction  is  obtained,  the  appearance  of  root 
roughness  due  to  angle  cannot  be  mistaken  for  absorption 
of  the  root.  There  is  a  radiolucent  area  in  the  mesial  sur- 
face of  the  first  bicuspid  which  has  the  appearance  of  a 
carious  cavity;  it  is  the  interproximal  space. 

Figs.  122  and  123.  Two  radiographs  of  the  same  case 
made  at  different  angles.  See  how  distinct  the  outlines 
of  the  roots  of  the  molar  are  in  one  view  and  how  indis- 
tinct they  are  in  the  other. 

Fig.  124.  The  radiolucent  spots  at  the  apices  of  the 
roots  of  the  third  molar  (the  first  molar  is  missing)  look 
very  suspicious  and  they  cannot  be  cast  away  from  the 
ends  of  the  roots  by  changing  angle.  They  are  at  the 
apices  of  the  roots.  The  electric  test  is  definitely  positive 
(+).  The  reason  for  the  small  radiolucent  areas  is  that 
the  roots  of  the  teeth  are  not  quite  fully  formed.  Note 
the  funnel  shaped  open  end  of  the  root.  (Radiograph  by 
Eller,  Albuquerque.) 

Fig.  125.  Same  case  as  Fig.  124,  other  side  of  the 
mouth. 


INTERPRETATION    OF    RADIOGRAPHS 


145 


Fig.  120. 


Fig.   121. 


Fig.   122. 


Fig.   123 


Fig.  124. 


Fig.   12.S. 


146  ELECTPvO-RADIOGRAPHIC    DIAGNOSIS 


Fig.  126.  The  abscess  illustrated  here  is  larger  than 
an  antrum.  Obviously  the  first  bicuspid  is  pulpless  for  we 
see  canal  filling  in  the  canals.  The  roots  of  the  cuspid 
and  second  bicuspid  seem  to  have  their  apices  absorbed. 
These  teeth  gave  a  negative  (-)  reaction  to  the  electric 
test  for  pulp  vitality.  After  extraction  it  could  be  seen 
that  these  root  ends  had  been  destroyed  just  as  they  ap- 
pear to  be  in  the  radiograph.  The  crown  was  removed 
from  the  lateral  incisor  and  the  electric  test  applied.  It 
was  negative  (-).  This  tooth  also  was  involved  in  the 
abscess.  The  central  incisor,  which  does  not  show  in  the 
negative,  also  was  involved  as  seen  in  another  negative 
not  reproduced  here. 

The  electric  test  is  of  extreme  value  in  checking  up 
such  unusual  findings  as  these. 

Fig.  127.  How  many  teeth  are  involved  in  the  abscess 
illustrated  here !  Frankly  I  cannot  tell.  I  am  reasonably 
sure  the  central  incisor,  with  the  canal  filling,  is  involved 
because  I  know  it  is  pulpless  and  because  its  apex  is  about 
in  the  mesio-distal  center  of  the  diseased  area.  But  are 
the  two  approximating  teeth  involved  1  That  is  the  ques- 
tion. And,  in  the  absence  of  electric  test  records,  I  can- 
not answer  it. 


iNTEKPRETATIOlSr    OF    RADIOGRAPHS 


147 


Fig.   126. 


Fig.   127. 


148  ELECTRO-EADIOGEAPHIC   DIAGISrOSIS 

Figs.  128  and  129.  Two  radiograplis  from  different 
angles,  another  case  in  wliicli  I  do  not  have  electric  test 
records.  Therefore  I  do  not  know  whether  the  lateral  in- 
cisor is  involved  in  the  abscess  or  not.  I  think  it  is,  but 
I  wonld  depend  on  the  electric  test  to  verify  this  opinion. 
If  the  tooth  has  a  vital  pulp  it  is  not  abscessed.  If  it  does 
not  have  a  vital  pnlp,  it  very  likely  is  abscessed. 

It  is  interesting  to  know  that  this  case  was  brought  to 
the  writer's  attention  as  an  example  of  failure  of  the  root 
end  resection  operation  to  cure  a  focus  of  infection — in 
short  as  an  argument  against  root  resection.  It  seems  to 
me  to  be  a  mighty  poor  argument  against  root  resection. 
No  wonder  we  have  failure  in  this  case.  The  cuspid  is 
loulpless  and  infected,  the  central  also  and  perhaps  the 
lateral  incisor.  The  operator  resected  only  the  buccal 
root  of  the  first  bicuspid.  The  lingual  root,  with  a  very 
imperfect  canal  filling  in  it,  remains  untouched  as  can  be 
seen  in  Fig.  128.  The  stub  of  the  buccal  root  is  not 
patched  with  amalgam.  It  is  not  good  judgment  to  draw 
one's  opinion  of  the  possibilities  of  the  root  resection 
operation  from  cases  like  this. 

Fig.  130.  Symptoms  those  of  semiacute  dentoalveolar 
abscess  with  sinus  discharging  pus  in  apical  region  be- 
tween central  and  lateral  incisors.  The  radiograph  shows 
bone  destruction  along  the  sides  of  the  roots  between  the 
central  and  lateral  incisors  near  the  apices  but  without 
definitely  involving  the  apices.  Resj)onse  to  electric  test 
a  definite  positive  (+).  Conclusion:  One  of  those  com- 
paratively rare  cases  of  "pyorrhea"  where,  instead  of 
the  pus  discharging  about  the  neck  of  the  tooth  it  dis- 
charges like  a  dentoalveolar  abscess  through  the  external 
alveolar  plate. 

The  treatment  indicated  for  pyorrhea  is  vastly  differ- 
ent from  that  indicated  for  a  dentoalveolar  abscess. 
Hence  the  necessity  of  correct  diagnosis.  This  case  was 
treated  in  accord  with  the  diagnosis  given  above  and 
yielded  to  the  treatment. 


INTERPRETATION"    OF    RADIOGRAPHS 


149 


Fig.   128. 


Fig.   129. 


Fig.   130. 


150  ELECTRO-RADIOGRAPHIC    DIAGNOSIS 


Fig.  131.  Another  case  in  whicli  pyorrhea  had  the 
symptomatic  appearance  of  a  dentoalveolar  abscess.  But 
the  electric  test  and  the  radiograph  combined  to  make  a 
correct  diagnosis. 

The  writer  has  encountered  a  few  cases  similar  to  Figs. 
130  and  131,  in  which  the  trouble  was  caused  by  a  silk 
ligature,  or  a  ring  of  rubber  dam,  left  on  the  tooth.  The 
ligature,  or  rubber  ring  jerked  out  of  the  rubber  dam 
when  removed  carelessly  and  hastily,  particularly  the  lat- 
ter, works  beneath  the  gum  toward  the  root  end  causing 
a  great  deal  of  inflammation  and  loosening  of  the  tooth  or 
teeth.  The  electric  test  is  very  valuable  in  such  cases  as 
the  symptoms  simulate  abscess  very  closely.  Orthodontic 
elastics  encircling  one  or  more  teeth  have  been  known  to 
escape  under  the  gum  and  cause  the  same  trouble  as- 
cribed to  ligatures  and  rings  of  rubber  dam. 

Fig.  132.  The  third  molar  responded  positive  very 
strong  (+VS)  to  the  electric  test.  The  reason  is  the  large 
carious  cavity  in  the  mesial  surface.  The  outlines  of  the 
roots  are  indistinct,  not  due  to  angle  but  to  hypercemento- 
sis.  Hypercementosis  occurs  much  more  frequently  in 
pulpless  teeth  than  in  teetli  with  vital  pulps. 

Fig.  133.  There  is  a  radiolucent  spot  at  the  bifurcation 
of  the  roots  of  the  lower  first  molar.  The  tooth  is  nega- 
tive (-)  to  the  electric  test.  The  tooth  is  abscessed, 
though  there  is  no  radiographic  evidence  of  it  at  the 
apices  of  the  roots.  The  dark  area  at  the  bifurcation  is 
caused  by  a  perforation  of  external  alveolar  plate,  i.e.,  a 
hole  in  the  external  alveolar  plate.  This  perforation  of 
the  external  plate  of  bone  on  a  level  with  the  bifurcation 
of  the  roots  is  due  to  the  tliickness  of  the  oblique  ridges. 
If,  my  reader,  you  are  inclined  to  incredulity,  let  me  say 
I  have  a  dry  specimen  closely  analogous  to  Fig.  133. 


INTERPRETATIOlSr    OF    RADIOGRAPHS 


151 


Fig.   131. 


Fig:.   132. 


Fig.   133. 


152  ELECTRO-EADIOGRAPHIC    DIAGNOSIS 


Fig.  134.  Note  tlie  radiolucent  area  just  above  the  bi- 
furcation of  the  roots  of  the  second  molar.  Tooth  re- 
sponds positive  strong  (+S)  to  the  electric  test.  The 
radiolucent  area  is  a  large  carious  cavity  beneath  the  gum 
line  on  the  buccal. 

Fig.  135,  The  oblique  ridges  cast  a  sort  of  haze  over 
the  apical  region  of  lower  molars  in  some  cases,  so  that 
the  operator  may  overlook  an  area  of  radiolucency  if  he  is 
not  careful.  Seeing  an  abscess  area  through  the  oblique 
ridges  is  rather  similar  to  observing  something  through 
a  fog.  When  a  lower  molar  is  known  to  be,  or  thought  to 
be,  without  a  vital  pulp,  one  is  more  careful  in  one's  ex- 
amination of  the  periapical  tissues.  Hence  the  value  of 
the  test  to  determine  pulp  vitality. 

Fig.  135  is  overdeveloped  and  published  without  re- 
touching. It  shows  the  haze  of  radiopacity  cast  by  the 
oblique  ridges.  In  the  negative  now  before  me,  I  can  see 
a  radiolucent  abscess  area,  through  the  haze  of  the  ridges, 
at  the  apex  of  the  molar  tooth. 


INTERPKETATIOlSr    OF    RADIOGRAPHS 


153 


Fig.  134. 


Fig.   135. 


154  ELECTEO-RADIOGEAPHIC    DIAGNOSIS 

Conclusion 

My  objective  in  tliis  chapter  lias  been  to  prove  the 
electric  test  necessary  to  the  correct  and  reliable  inter- 
pretation of  radiographs  and  therefore  necessary  to  the 
art  of  dental  diagnoses.  I  conld  go  on  indefinitely  citing 
case  after  case,  just  as  one  could  go  on  indefinitely  citing 
case  after  case  to  prove  the  usefulness  of  the  radiograph 
in  the  practice  of  dentistry,  but  it  is  not  necessary.  /'  Re- 
lieve I  have  attained  my  objective.  I  believe  I  have 
proved  the  value  of  the  test  and  so  I  submit  no  further 
evidence  but  "let  my  case  rest  with  the  jury." 


INDEX 

A 

Abrasion,  78 

Abscess  (also  see  differentiation),  108,  109,  110 

cavity,  101 

failure  to  show  in  radiograph,  118 

lapping  the  teeth,  112 

number  of  teeth  involved,  105 

of  tooth  with  vital  pulp,  19 

shadows  overlapping,  122,  124,  126 

under  silicious  cement  fillings,  11!^ 

very  large,  146 
Absence  of  x-ray  machine,  98 
Absorption,  appearance  of,  due  to  angle,  105 

of  roots  upper  molars,  104 
Age,  75 

Amount  current  needed  for  test,  75 
Angle  of  x-rays,  99,  100,  105,  118,  122,  144 
Anterior  palatine  foramen,  101,  102,  132,  134 
Antrum  of  Highmore,  102,  136,  138 
Apparently  sound  teeth,  108,  109,  110 
Application  dental  electrode,  54 

B 

Bifurcation  roots,  lower  molars,  150 
Broken  cords,  35,  60  (Fig.  29) 

C 
Cancellous  spot,  104 
Cavity,  78,  144,  150,  152 
Cement  fillings,  112 
Changing  plugs,  61 
Chart,  diagnostic,  43 
Children,  90 

Choice  of  point  of  application  of  dental  electrode,  54 
Choke  coil,  31 
Clinic,  written,  87 
Clinical  value  of  test,  95,  96 
Contact,  moisture,  50,  51 
Controls  on  Faradic  machine,  45 

155 


156  INDEX 

Cords,  35 

broken,  35,  60  (Fig.  29) 
Cortical  bone  shadows,  138 
Cotton  holder,  41 
Crowned  teeth,  57 
Criticism  of  test  answered,  91,  94 
Current  (electric)  : 

amount  needed  to  test,  75 

gradation  of,  29,  45,  46,  47,  50 

immunity  to,  78,  79 

safety  and  danger,  24 

source  of.  23 

tracing  through  Faradic  machine,  24 

tracing  when  used,  48 
Cyst,  136 

D 

Danger  of  current,  24 

Dead  pulps  without  periapical  bone  change,  99,  116 

Defect,  in  Faradic  machine,  28,  29 

Dental  electrode,  36,  37 

wrapping,  52 
Dental  mouth  mirror,  42 
Dental  switchboard,  30 
Dentin,  exposed,  78 

secondary,  76,  114,  140,  142 
Dento-alveolar  abscess,  (see  abscess) 
Diagnosis,  dijfferential  (see  differentiation) 
Diagnostic  chart,  43 
Diagnostic  opening,  77 
Differentiation : 

abscess  and  anterior  palatine  foramen,  101,  102,  132,  134 

abscess  and  antrum,  102,  136,  138 

abscess  and  incisive  foramen,  101,  102 

abscess  and  large  cancellous  spot,  104 

abscess  and  large  periapical  space,  104 

abscess  and  mental  foramen,  101,  126,  to  130 

abscess  and  nasal  fossae  spots,  103,  140,  142 

abscess  and  nostril  spots,  103 

abscess  and  partially  formed  root,  105,  144 

abscess  and  pyorrhea,  106,  148,  150 

abscess  and  radiolucent  area  in  region  of  upper  lateral  in- 
cisors, 103,  140 

between  pulpal  and  gingival  sensation,  81,  82 
Disto-buccal  roots,  142 


INDEX  157 

E 


Electric  test  (see  test) 
Electrode,  dental,  36,  37 

hand,  or  indifferent,  38 

wrapping,  52 
Electrophobia,  86 

Effect  of  fillings  on  current  needed,  79,  80 
Enamel,  thickness  of,  75 

unsupported,  59 
Erosion,  78 
Exposed  dentin,  78 

F 

Factors  modifying  current  needed,  75 
Faradic  machine,  23,  28 

appearance,  25 

controls,  45 

defect  of,  and  how  to  overcome,  28,  29 

modified,  26,  28 

parts  of,  24 

safety  of,  24 

three  sockets,  29,  45,  46 

tracing  current  through,  24 

transportability,  26 
Fillings,  cement,  112 

effect  on  current  needed,  79,  80 

large,  57 

silieious  cement,  112 
Fistulous  tract,  110 
Foramen,  anterior  palatine,  101,  102,  132,  134 

incisive  (see  anterior  palatine) 

mental,  101,  126  to  130 
Fossai,  nasal,  103,  140,  142 

G 

Gradation  of  current,  29,  45,  46,  47,  50 

H 

High-frequency  machine,  32 


Immunitv  to  current,  78,  79 
Incisive  foramen,  101,  102,  132,  134 
Indistinct  root  outlines,  144 
Inferior  dental  canal,  103 


158  INDEX 

Insulation  of  teeth,  58 
Ionization  machine,  30 
Irritation  point,  47 

L 
Lamina  dnra,  126 
Large  fillings  in  teeth,  57 
Limitations  of  the  test,  83,  85 

M 

Machines  for  pnlp  testing,  23 

choke  coil,  31 

Faradic,  23,  29 

flashlight,  33,  34 

high-frequency,  32 

ionization,  30 

switchboard,  30,  31 

testing  out,  61 

transformer,  31 

x-ray,  absence  of,  98 
Maxillary  sinus,  102,  136,  138 
Medicine  dish,  42 
Mental  foramen,  101,  126-130 
Mirror,  dental  mouth,  42 
Missing  test  records,  122,  124 
Modified  Faradic  machine,  26,  28 
Moisture,  51,  52,  76 
Moisture  contact,  50,  51 
Molars,  upper,  roots  of,  104 

N 
Narcotics,  76 
Nasal  fossae,  103,  140,  142 
Nervous  patients,  86,  89 
Nostril  spots,  103 
Number  of  teeth  involved  in  abscess,  105 

0 

Oblique  ridges,  152 
Opening,  diagnostic,  77 
Osteoclasia  (also  see  abscess),  100 
Outfit  (for  pulp  testing),  35 
Overlapping  abscess  shadows,  122,  124,  126 


Pain,  56,  57 

Parts  of  Faradic  machine,  24 


INDEX  159 

Patients,  children  as,  90 

nervous,  86,  89 
Periapical  space,  large,  104 
Pericementitis,  80,  120 
Peridontoclasia  (see  pyorrhea) 
Plugs,  35 

changing,  61 
Polarity,  45 
Pulp,  dead  without  osteoclasia,  99,  116 

recession,  140 

stones,  78,  114 

testers  (also  see  machines),  23 
Pyorrhea,  106,  148,  150 

R 

Eadiolucent  area  in  region  of  upper  lateral  incisors,  103,  140 

Recession  of  pulps,  140 

Record  blanks,  42,  44 

Response  from  abscessed  tooth,  92,  93 

Root,  outlines,  indistinct,  144 

partially  formed,  105,  144 

resection,  148 
Roots,  bifurcation  of,  lower  molars,  150 

disto-buccal,  142 

of  upper  molars,  104 
Rubber  dam  insulation,  58 

V     S 
Safety  and  danger  of  current,  24 
Secondary  dentin,  76,  114,  140,  142 
Sensation,  56,  57 

Shadows  overlapping,  122,  124,  126 
Shock,  24,  61 
Silicious  cement,  112 
Sinus,  maxillary,  102,  136,  138 
Sockets,  Faradic  machine,  29,  45,  46 
Sound  teeth  (apparently),  108,  109,  110 
Source  of  current,  23  • 
Suspicious  areas,  114 
Switchboard  (dental),  30 
Systemic  disease,  96,  97 


T 


Technic : 

fundamentals,  45,  49 
handling  children,  90 


160  INDEX 

illustrated,  63-74 

of  application  of  electrode  to  teetli,  54,  55 

of  applying  electrode  to  filling,  58,  59 

of  applying  test  for  nervous  patients,  86,  89 

of  controlling  tongue,  52 

of  keeping  teeth  dry,  51,  52 

of  making  moisture  contact,  50 

of  wrapping  dental  electrode,  52 

of  steadying  hand,  51 

valuable  point,  50 
Teeth : 

crowned,  57 

insulation  of,  58 

sound,  apparently,  108,  109,  110 

with  large  fillings,  57 
Test  (electric)  : 

advantage  of,  21 

compared  to  other  tests,  20 

harmless,  86 

limitations  of,  83,  85 

records,  missing,  122,  124 

reliability  of,  21 

safety  of,  21 

to  check  all  x-ray  findings,  98,  99 

value  of,  95,  96 
Testing  machines  (also  see  machines),  23 
Testing  out  machine,  61 
Testing  outfit,  35 

Transportability  of  Faradic  machine,  26 
Tracing  current  used,  48 
Tract,  fistulous,  110 
Transformer,  31 
Trouble,  59,  60 
Tweezers,  (cotton),  42 


Unsupported  enamel,  59 
Upper  molar  roots,  104 

Value  of  test,  95,  96 


U 
V 

w 


Wrapping  dental  electrode,  52 
Written  clinic,  87 

X 
X-ray  angles,  99,  100,  105,  118,  122,  144 
X-ray  machine,  absence  of,  98 


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